diff --git a/antarest/core/filesystem_blueprint.py b/antarest/core/filesystem_blueprint.py
index 10145d744e..2016cd47cf 100644
--- a/antarest/core/filesystem_blueprint.py
+++ b/antarest/core/filesystem_blueprint.py
@@ -203,7 +203,7 @@ async def from_path(cls, full_path: Path, *, details: bool = False) -> "FileInfo
         return obj
 
 
-async def _calc_details(full_path: t.Union[str, Path]) -> t.Tuple[int, int]:
+async def _calc_details(full_path: str | Path) -> t.Tuple[int, int]:
     """Calculate the number of files and the total size of a directory recursively."""
 
     full_path = Path(full_path)
diff --git a/antarest/core/permissions.py b/antarest/core/permissions.py
index 9bf073e809..b26c2c51b4 100644
--- a/antarest/core/permissions.py
+++ b/antarest/core/permissions.py
@@ -20,7 +20,7 @@
 logger = logging.getLogger(__name__)
 
 
-permission_matrix: t.Dict[str, t.Dict[str, t.Sequence[t.Union[RoleType, PublicMode]]]] = {
+permission_matrix: t.Dict[str, t.Dict[str, t.Sequence[RoleType | PublicMode]]] = {
     StudyPermissionType.READ.value: {
         "roles": [
             RoleType.ADMIN,
diff --git a/antarest/core/serialization/__init__.py b/antarest/core/serialization/__init__.py
index 5591290ce8..4cc9ed550a 100644
--- a/antarest/core/serialization/__init__.py
+++ b/antarest/core/serialization/__init__.py
@@ -22,7 +22,7 @@
 # Since pydantic v2 is written in RUST it's way faster.
 
 
-def from_json(data: t.Union[str, bytes, bytearray]) -> t.Dict[str, t.Any]:
+def from_json(data: str | bytes | bytearray) -> t.Dict[str, t.Any]:
     return ADAPTER.validate_json(data)  # type: ignore
 
 
diff --git a/antarest/core/tasks/service.py b/antarest/core/tasks/service.py
index 4ada902c58..22c70e0d42 100644
--- a/antarest/core/tasks/service.py
+++ b/antarest/core/tasks/service.py
@@ -69,7 +69,7 @@ def add_worker_task(
         self,
         task_type: TaskType,
         task_queue: str,
-        task_args: t.Dict[str, t.Union[int, float, bool, str]],
+        task_args: t.Dict[str, int | float | bool | str],
         name: t.Optional[str],
         ref_id: t.Optional[str],
         request_params: RequestParameters,
@@ -178,7 +178,7 @@ def _create_worker_task(
         self,
         task_id: str,
         task_type: str,
-        task_args: t.Dict[str, t.Union[int, float, bool, str]],
+        task_args: t.Dict[str, int | float | bool | str],
     ) -> Task:
         task_result_wrapper: t.List[TaskResult] = []
 
@@ -227,7 +227,7 @@ def add_worker_task(
         self,
         task_type: TaskType,
         task_queue: str,
-        task_args: t.Dict[str, t.Union[int, float, bool, str]],
+        task_args: t.Dict[str, int | float | bool | str],
         name: t.Optional[str],
         ref_id: t.Optional[str],
         request_params: RequestParameters,
diff --git a/antarest/launcher/model.py b/antarest/launcher/model.py
index df5c9cb903..25c12f711c 100644
--- a/antarest/launcher/model.py
+++ b/antarest/launcher/model.py
@@ -39,7 +39,7 @@ class LauncherParametersDTO(AntaresBaseModel):
     nb_cpu: t.Optional[int] = None
     post_processing: bool = False
     time_limit: int = 240 * 3600  # Default value set to 240 hours (in seconds)
-    xpansion: t.Union[XpansionParametersDTO, bool, None] = None
+    xpansion: XpansionParametersDTO | bool | None = None
     xpansion_r_version: bool = False
     archive_output: bool = True
     auto_unzip: bool = True
diff --git a/antarest/matrixstore/model.py b/antarest/matrixstore/model.py
index b117e12e1f..e63dda439a 100644
--- a/antarest/matrixstore/model.py
+++ b/antarest/matrixstore/model.py
@@ -237,8 +237,8 @@ class MatrixContent(AntaresBaseModel):
     """
 
     data: t.List[t.List[MatrixData]]
-    index: t.List[t.Union[int, str]]
-    columns: t.List[t.Union[int, str]]
+    index: t.List[int | str]
+    columns: t.List[int | str]
 
 
 class MatrixDataSetUpdateDTO(AntaresBaseModel):
diff --git a/antarest/matrixstore/repository.py b/antarest/matrixstore/repository.py
index 4b8aa7840e..853b812908 100644
--- a/antarest/matrixstore/repository.py
+++ b/antarest/matrixstore/repository.py
@@ -181,7 +181,7 @@ def exists(self, matrix_hash: str) -> bool:
         matrix_file = self.bucket_dir.joinpath(f"{matrix_hash}.tsv")
         return matrix_file.exists()
 
-    def save(self, content: t.Union[t.List[t.List[MatrixData]], npt.NDArray[np.float64]]) -> str:
+    def save(self, content: t.List[t.List[MatrixData]] | npt.NDArray[np.float64]) -> str:
         """
         Saves the content of a matrix as a TSV file in the bucket directory
         and returns its SHA256 hash.
diff --git a/antarest/matrixstore/service.py b/antarest/matrixstore/service.py
index ca69f40fa2..50e5d254c7 100644
--- a/antarest/matrixstore/service.py
+++ b/antarest/matrixstore/service.py
@@ -72,7 +72,7 @@ def __init__(self, matrix_content_repository: MatrixContentRepository) -> None:
         self.matrix_content_repository = matrix_content_repository
 
     @abstractmethod
-    def create(self, data: t.Union[t.List[t.List[MatrixData]], npt.NDArray[np.float64]]) -> str:
+    def create(self, data: t.List[t.List[MatrixData]] | npt.NDArray[np.float64]) -> str:
         raise NotImplementedError()
 
     @abstractmethod
@@ -87,7 +87,7 @@ def exists(self, matrix_id: str) -> bool:
     def delete(self, matrix_id: str) -> None:
         raise NotImplementedError()
 
-    def get_matrix_id(self, matrix: t.Union[t.List[t.List[float]], str]) -> str:
+    def get_matrix_id(self, matrix: t.List[t.List[float]] | str) -> str:
         """
         Get the matrix ID from a matrix or a matrix link.
 
@@ -114,7 +114,7 @@ def __init__(self, matrix_content_repository: MatrixContentRepository):
         super().__init__(matrix_content_repository=matrix_content_repository)
 
     @override
-    def create(self, data: t.Union[t.List[t.List[MatrixData]], npt.NDArray[np.float64]]) -> str:
+    def create(self, data: t.List[t.List[MatrixData]] | npt.NDArray[np.float64]) -> str:
         return self.matrix_content_repository.save(data)
 
     @override
@@ -171,7 +171,7 @@ def _from_dto(dto: MatrixDTO) -> t.Tuple[Matrix, MatrixContent]:
         return matrix, content
 
     @override
-    def create(self, data: t.Union[t.List[t.List[MatrixData]], npt.NDArray[np.float64]]) -> str:
+    def create(self, data: t.List[t.List[MatrixData]] | npt.NDArray[np.float64]) -> str:
         """
         Creates a new matrix object with the specified data.
 
diff --git a/antarest/study/business/aggregator_management.py b/antarest/study/business/aggregator_management.py
index 6ee055bf2f..83a44ddc8f 100644
--- a/antarest/study/business/aggregator_management.py
+++ b/antarest/study/business/aggregator_management.py
@@ -146,7 +146,7 @@ def __init__(
         self,
         study_path: Path,
         output_id: str,
-        query_file: t.Union[MCIndAreasQueryFile, MCAllAreasQueryFile, MCIndLinksQueryFile, MCAllLinksQueryFile],
+        query_file: MCIndAreasQueryFile | MCAllAreasQueryFile | MCIndLinksQueryFile | MCAllLinksQueryFile,
         frequency: MatrixFrequency,
         ids_to_consider: t.Sequence[str],
         columns_names: t.Sequence[str],
diff --git a/antarest/study/business/areas/st_storage_management.py b/antarest/study/business/areas/st_storage_management.py
index dceeda6956..12769da8b5 100644
--- a/antarest/study/business/areas/st_storage_management.py
+++ b/antarest/study/business/areas/st_storage_management.py
@@ -584,7 +584,7 @@ def duplicate_cluster(self, study: Study, area_id: str, source_id: str, new_clus
         ]
 
         # Prepare and execute commands
-        commands: t.List[t.Union[CreateSTStorage, ReplaceMatrix]] = [create_cluster_cmd]
+        commands: t.List[CreateSTStorage | ReplaceMatrix] = [create_cluster_cmd]
         storage_service = self.storage_service.get_storage(study)
         command_context = self.storage_service.variant_study_service.command_factory.command_context
         for source_path, new_path in zip(source_paths, new_paths):
diff --git a/antarest/study/business/areas/thermal_management.py b/antarest/study/business/areas/thermal_management.py
index c78ab6217f..811f5765d0 100644
--- a/antarest/study/business/areas/thermal_management.py
+++ b/antarest/study/business/areas/thermal_management.py
@@ -464,7 +464,7 @@ def duplicate_cluster(
             new_paths.append(f"input/thermal/series/{area_id}/{lower_new_id}/fuelCost")
 
         # Prepare and execute commands
-        commands: t.List[t.Union[CreateCluster, ReplaceMatrix]] = [create_cluster_cmd]
+        commands: t.List[CreateCluster | ReplaceMatrix] = [create_cluster_cmd]
         storage_service = self.storage_service.get_storage(study)
         command_context = self.storage_service.variant_study_service.command_factory.command_context
         for source_path, new_path in zip(source_paths, new_paths):
diff --git a/antarest/study/business/binding_constraint_management.py b/antarest/study/business/binding_constraint_management.py
index e18fcc0564..6c66f04001 100644
--- a/antarest/study/business/binding_constraint_management.py
+++ b/antarest/study/business/binding_constraint_management.py
@@ -145,7 +145,7 @@ class ConstraintTerm(AntaresBaseModel):
     id: t.Optional[str] = None
     weight: t.Optional[float] = None
     offset: t.Optional[int] = None
-    data: t.Optional[t.Union[LinkTerm, ClusterTerm]] = None
+    data: t.Optional[LinkTerm | ClusterTerm] = None
 
     @field_validator("id")
     def id_to_lower(cls, v: t.Optional[str]) -> t.Optional[str]:
@@ -348,7 +348,7 @@ class ConstraintOutput870(ConstraintOutput830):
 
 # WARNING: Do not change the order of the following line, it is used to determine
 # the type of the output constraint in the FastAPI endpoint.
-ConstraintOutput = t.Union[ConstraintOutputBase, ConstraintOutput830, ConstraintOutput870]
+ConstraintOutput = ConstraintOutputBase | ConstraintOutput830 | ConstraintOutput870
 
 OPERATOR_MATRIX_FILE_MAP = {
     BindingConstraintOperator.EQUAL: ["{bc_id}_eq"],
@@ -1177,7 +1177,7 @@ def _replace_matrices_according_to_frequency_and_version(
 
 
 def check_attributes_coherence(
-    data: t.Union[ConstraintCreation, ConstraintInput],
+    data: ConstraintCreation | ConstraintInput,
     study_version: StudyVersion,
     operator: BindingConstraintOperator,
 ) -> None:
diff --git a/antarest/study/business/scenario_builder_management.py b/antarest/study/business/scenario_builder_management.py
index 0ea15dd6d8..8ce3b9345d 100644
--- a/antarest/study/business/scenario_builder_management.py
+++ b/antarest/study/business/scenario_builder_management.py
@@ -31,7 +31,7 @@
 
 _HYDRO_LEVEL_PERCENT = 100
 
-_Section: te.TypeAlias = t.MutableMapping[str, t.Union[int, float]]
+_Section: te.TypeAlias = t.MutableMapping[str, int | float]
 _Sections: te.TypeAlias = t.MutableMapping[str, _Section]
 
 Ruleset: te.TypeAlias = t.MutableMapping[str, t.Any]
@@ -92,11 +92,11 @@ def _get_ruleset_config(
     file_study: FileStudy,
     ruleset_name: str,
     symbol: str = "",
-) -> t.Dict[str, t.Union[int, float]]:
+) -> t.Dict[str, int | float]:
     try:
         suffix = f"/{symbol}" if symbol else ""
         url = f"settings/scenariobuilder/{ruleset_name}{suffix}".split("/")
-        ruleset_cfg = t.cast(t.Dict[str, t.Union[int, float]], file_study.tree.get(url))
+        ruleset_cfg = t.cast(t.Dict[str, int | float], file_study.tree.get(url))
     except KeyError:
         ruleset_cfg = {}
     return ruleset_cfg
diff --git a/antarest/study/business/xpansion_management.py b/antarest/study/business/xpansion_management.py
index 7464de5ec5..4450db44b7 100644
--- a/antarest/study/business/xpansion_management.py
+++ b/antarest/study/business/xpansion_management.py
@@ -703,7 +703,7 @@ def get_resource_content(
         study: Study,
         resource_type: XpansionResourceFileType,
         filename: str,
-    ) -> t.Union[JSON, bytes]:
+    ) -> JSON | bytes:
         logger.info(f"Getting xpansion {resource_type} resource file '{filename}' from study '{study.id}'")
         file_study = self.study_storage_service.get_storage(study).get_raw(study)
         return file_study.tree.get(self._raw_file_dir(resource_type) + [filename])
diff --git a/antarest/study/common/studystorage.py b/antarest/study/common/studystorage.py
index 221857c339..3bffa67f0e 100644
--- a/antarest/study/common/studystorage.py
+++ b/antarest/study/common/studystorage.py
@@ -116,7 +116,7 @@ def patch_update_study_metadata(self, study: T, metadata: StudyMetadataPatchDTO)
     def import_output(
         self,
         study: T,
-        output: t.Union[t.BinaryIO, Path],
+        output: t.BinaryIO | Path,
         output_name: t.Optional[str] = None,
     ) -> t.Optional[str]:
         """
diff --git a/antarest/study/model.py b/antarest/study/model.py
index d2ff8b97b9..4dbacf2ec9 100644
--- a/antarest/study/model.py
+++ b/antarest/study/model.py
@@ -431,7 +431,7 @@ class StudyMetadataDTO(AntaresBaseModel):
     tags: t.List[str] = []
 
     @field_validator("horizon", mode="before")
-    def transform_horizon_to_str(cls, val: t.Union[str, int, None]) -> t.Optional[str]:
+    def transform_horizon_to_str(cls, val: str | int | None) -> t.Optional[str]:
         # horizon can be an int.
         return str(val) if val else val  # type: ignore
 
diff --git a/antarest/study/repository.py b/antarest/study/repository.py
index a904124d4d..1cb08da490 100644
--- a/antarest/study/repository.py
+++ b/antarest/study/repository.py
@@ -59,7 +59,7 @@ class AccessPermissions(AntaresBaseModel, frozen=True, extra="forbid"):
     user_groups: t.Sequence[str] = ()
 
     @classmethod
-    def from_params(cls, params: t.Union[RequestParameters, JWTUser]) -> "AccessPermissions":
+    def from_params(cls, params: RequestParameters | JWTUser) -> "AccessPermissions":
         """
         This function makes it easier to pass on user ids and groups into the repository filtering function by
         extracting the associated `AccessPermissions` object.
diff --git a/antarest/study/service.py b/antarest/study/service.py
index 31bb80fa1f..0aff0459ae 100644
--- a/antarest/study/service.py
+++ b/antarest/study/service.py
@@ -181,7 +181,7 @@
 MAX_MISSING_STUDY_TIMEOUT = 2  # days
 
 
-def get_disk_usage(path: t.Union[str, Path]) -> int:
+def get_disk_usage(path: str | Path) -> int:
     """Calculate the total disk usage (in bytes) of a study in a compressed file or directory."""
     path = Path(path)
     if is_archive_format(path.suffix.lower()):
@@ -213,7 +213,7 @@ def _imports_matrix_from_bytes(data: bytes) -> npt.NDArray[np.float64]:
 
 
 def _get_path_inside_user_folder(
-    path: str, exception_class: t.Type[t.Union[FolderCreationNotAllowed, ResourceDeletionNotAllowed]]
+    path: str, exception_class: t.Type[FolderCreationNotAllowed | ResourceDeletionNotAllowed]
 ) -> str:
     """
     Retrieves the path inside the `user` folder for a given user path
@@ -498,7 +498,7 @@ def aggregate_output_data(
         self,
         uuid: str,
         output_id: str,
-        query_file: t.Union[MCIndAreasQueryFile, MCAllAreasQueryFile, MCIndLinksQueryFile, MCAllLinksQueryFile],
+        query_file: MCIndAreasQueryFile | MCAllAreasQueryFile | MCIndLinksQueryFile | MCAllLinksQueryFile,
         frequency: MatrixFrequency,
         columns_names: t.Sequence[str],
         ids_to_consider: t.Sequence[str],
@@ -594,7 +594,7 @@ def save_logs(
         )
         stopwatch.log_elapsed(lambda d: logger.info(f"Saved logs for job {job_id} in {d}s"))
 
-    def get_comments(self, study_id: str, params: RequestParameters) -> t.Union[str, JSON]:
+    def get_comments(self, study_id: str, params: RequestParameters) -> str | JSON:
         """
         Get the comments of a study.
 
@@ -1360,7 +1360,7 @@ def download_outputs(
         filetype: ExportFormat,
         params: RequestParameters,
         tmp_export_file: t.Optional[Path] = None,
-    ) -> t.Union[Response, FileDownloadTaskDTO, FileResponse]:
+    ) -> Response | FileDownloadTaskDTO | FileResponse:
         """
         Download outputs
         Args:
@@ -1551,7 +1551,7 @@ def import_study(
     def import_output(
         self,
         uuid: str,
-        output: t.Union[t.BinaryIO, Path],
+        output: t.BinaryIO | Path,
         params: RequestParameters,
         output_name_suffix: t.Optional[str] = None,
         auto_unzip: bool = True,
@@ -1896,7 +1896,7 @@ def get_all_areas(
         area_type: t.Optional[AreaType],
         ui: bool,
         params: RequestParameters,
-    ) -> t.Union[t.List[AreaInfoDTO], t.Dict[str, t.Any]]:
+    ) -> t.List[AreaInfoDTO] | t.Dict[str, t.Any]:
         study = self.get_study(uuid)
         assert_permission(params.user, study, StudyPermissionType.READ)
         return self.areas.get_all_areas_ui_info(study) if ui else self.areas.get_all_areas(study, area_type)
@@ -2817,9 +2817,9 @@ def create_user_folder(self, study_id: str, path: str, current_user: JWTUser) ->
     def _alter_user_folder(
         self,
         study_id: str,
-        command_data: t.Union[CreateUserResourceData, RemoveUserResourceData],
-        command_class: t.Type[t.Union[CreateUserResource, RemoveUserResource]],
-        exception_class: t.Type[t.Union[FolderCreationNotAllowed, ResourceDeletionNotAllowed]],
+        command_data: CreateUserResourceData | RemoveUserResourceData,
+        command_class: t.Type[CreateUserResource | RemoveUserResource],
+        exception_class: t.Type[FolderCreationNotAllowed | ResourceDeletionNotAllowed],
         current_user: JWTUser,
     ) -> None:
         study = self.get_study(study_id)
diff --git a/antarest/study/storage/abstract_storage_service.py b/antarest/study/storage/abstract_storage_service.py
index 69d9ba6a27..d5937600d2 100644
--- a/antarest/study/storage/abstract_storage_service.py
+++ b/antarest/study/storage/abstract_storage_service.py
@@ -254,7 +254,7 @@ def get_study_sim_result(
     def import_output(
         self,
         metadata: T,
-        output: t.Union[t.BinaryIO, Path],
+        output: t.BinaryIO | Path,
         output_name: t.Optional[str] = None,
     ) -> t.Optional[str]:
         """
diff --git a/antarest/study/storage/df_download.py b/antarest/study/storage/df_download.py
index acb9471802..e0f2c25f75 100644
--- a/antarest/study/storage/df_download.py
+++ b/antarest/study/storage/df_download.py
@@ -71,7 +71,7 @@ def suffix(self) -> str:
     def export_table(
         self,
         df: pd.DataFrame,
-        export_path: t.Union[str, Path],
+        export_path: str | Path,
         *,
         with_index: bool = True,
         with_header: bool = True,
diff --git a/antarest/study/storage/patch_service.py b/antarest/study/storage/patch_service.py
index f98870e240..146c285ccb 100644
--- a/antarest/study/storage/patch_service.py
+++ b/antarest/study/storage/patch_service.py
@@ -30,7 +30,7 @@ class PatchService:
     def __init__(self, repository: t.Optional[StudyMetadataRepository] = None):
         self.repository = repository
 
-    def get(self, study: t.Union[RawStudy, VariantStudy], get_from_file: bool = False) -> Patch:
+    def get(self, study: RawStudy | VariantStudy, get_from_file: bool = False) -> Patch:
         if not get_from_file and study.additional_data is not None:
             # the `study.additional_data.patch` field is optional
             if study.additional_data.patch:
@@ -52,7 +52,7 @@ def get_from_filestudy(self, file_study: FileStudy) -> Patch:
 
     def set_reference_output(
         self,
-        study: t.Union[RawStudy, VariantStudy],
+        study: RawStudy | VariantStudy,
         output_id: str,
         status: bool = True,
     ) -> None:
@@ -63,7 +63,7 @@ def set_reference_output(
             patch.outputs = PatchOutputs(reference=output_id)
         self.save(study, patch)
 
-    def save(self, study: t.Union[RawStudy, VariantStudy], patch: Patch) -> None:
+    def save(self, study: RawStudy | VariantStudy, patch: Patch) -> None:
         if self.repository:
             study.additional_data = study.additional_data or StudyAdditionalData()
             study.additional_data.patch = patch.model_dump_json()
diff --git a/antarest/study/storage/rawstudy/ini_reader.py b/antarest/study/storage/rawstudy/ini_reader.py
index e003878e7c..5fb613b80a 100644
--- a/antarest/study/storage/rawstudy/ini_reader.py
+++ b/antarest/study/storage/rawstudy/ini_reader.py
@@ -21,13 +21,13 @@
 from antarest.core.model import JSON
 
 
-def convert_value(value: str) -> t.Union[str, int, float, bool]:
+def convert_value(value: str) -> str | int | float | bool:
     """Convert value to the appropriate type for JSON."""
 
     try:
         # Infinity values are not supported by JSON, so we use a string instead.
         mapping = {"true": True, "false": False, "+inf": "+Inf", "-inf": "-Inf", "inf": "+Inf"}
-        return t.cast(t.Union[str, int, float, bool], mapping[value.lower()])
+        return t.cast(str | int | float | bool, mapping[value.lower()])
     except KeyError:
         try:
             return int(value)
@@ -56,8 +56,8 @@ def from_kwargs(
         cls,
         section: str = "",
         option: str = "",
-        section_regex: t.Optional[t.Union[str, t.Pattern[str]]] = None,
-        option_regex: t.Optional[t.Union[str, t.Pattern[str]]] = None,
+        section_regex: t.Optional[str | t.Pattern[str]] = None,
+        option_regex: t.Optional[str | t.Pattern[str]] = None,
         **_unused: t.Any,  # ignore unknown options
     ) -> "IniFilter":
         """
diff --git a/antarest/study/storage/rawstudy/model/filesystem/config/ruleset_matrices.py b/antarest/study/storage/rawstudy/model/filesystem/config/ruleset_matrices.py
index 47a7568142..7cce665366 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/config/ruleset_matrices.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/config/ruleset_matrices.py
@@ -31,15 +31,15 @@
     "hgp": "hydro-generation-power",
 }
 
-_Value: te.TypeAlias = t.Union[int, float]
+_Value: te.TypeAlias = int | float
 _SimpleScenario: te.TypeAlias = pd.DataFrame
 _ClusterScenario: te.TypeAlias = t.MutableMapping[str, pd.DataFrame]
-_Scenario: te.TypeAlias = t.Union[_SimpleScenario, _ClusterScenario]
+_Scenario: te.TypeAlias = _SimpleScenario | _ClusterScenario
 _ScenarioMapping: te.TypeAlias = t.MutableMapping[str, _Scenario]
 
-SimpleTableForm: te.TypeAlias = t.Dict[str, t.Dict[str, t.Union[int, float, str, None]]]
+SimpleTableForm: te.TypeAlias = t.Dict[str, t.Dict[str, int | float | str | None]]
 ClusterTableForm: te.TypeAlias = t.Dict[str, SimpleTableForm]
-TableForm: te.TypeAlias = t.Union[SimpleTableForm, ClusterTableForm]
+TableForm: te.TypeAlias = SimpleTableForm | ClusterTableForm
 
 _AREA_RELATED_SYMBOLS = "l", "h", "w", "s", "hgp"
 _BINDING_CONSTRAINTS_RELATED_SYMBOLS = ("bc",)
@@ -315,7 +315,7 @@ def to_percent(v: t.Any) -> _Value:
             raise NotImplementedError(f"Unknown symbol {symbol}")
         return scenario_rules
 
-    def get_table_form(self, scenario_type: str, *, nan_value: t.Union[str, None] = "") -> TableForm:
+    def get_table_form(self, scenario_type: str, *, nan_value: str | None = "") -> TableForm:
         """
         Get the scenario matrices in table form for the frontend.
 
@@ -366,7 +366,7 @@ def set_table_form(
         table_form: TableForm,
         scenario_type: str,
         *,
-        nan_value: t.Union[str, None] = "",
+        nan_value: str | None = "",
     ) -> None:
         """
         Set the scenario matrix from table form data, for a specific scenario type.
diff --git a/antarest/study/storage/rawstudy/model/filesystem/config/st_storage.py b/antarest/study/storage/rawstudy/model/filesystem/config/st_storage.py
index 0d21455783..a2bb0ee714 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/config/st_storage.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/config/st_storage.py
@@ -160,7 +160,7 @@ class STStorage880Config(STStorage880Properties, LowerCaseIdentifier):
 
 # NOTE: In the following Union, it is important to place the older version first,
 # because otherwise, creating a short term storage always creates a v8.8 one.
-STStorageConfigType = t.Union[STStorageConfig, STStorage880Config]
+STStorageConfigType = STStorageConfig | STStorage880Config
 
 
 def get_st_storage_config_cls(study_version: StudyVersion) -> t.Type[STStorageConfigType]:
diff --git a/antarest/study/storage/rawstudy/model/filesystem/config/thermal.py b/antarest/study/storage/rawstudy/model/filesystem/config/thermal.py
index 87f20514f4..b5c46853fd 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/config/thermal.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/config/thermal.py
@@ -408,7 +408,7 @@ class Thermal870Config(Thermal870Properties, IgnoreCaseIdentifier):
 
 # NOTE: In the following Union, it is important to place the most specific type first,
 # because the type matching generally occurs sequentially from left to right within the union.
-ThermalConfigType = t.Union[Thermal870Config, Thermal860Config, ThermalConfig]
+ThermalConfigType = Thermal870Config | Thermal860Config | ThermalConfig
 
 
 def get_thermal_config_cls(study_version: StudyVersion) -> t.Type[ThermalConfigType]:
diff --git a/antarest/study/storage/rawstudy/model/filesystem/folder_node.py b/antarest/study/storage/rawstudy/model/filesystem/folder_node.py
index cfcebe9019..81409574f4 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/folder_node.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/folder_node.py
@@ -61,7 +61,7 @@ def _forward_get(
         depth: int = -1,
         formatted: bool = True,
         get_node: bool = False,
-    ) -> t.Union[JSON, INode[JSON, SUB_JSON, JSON]]:
+    ) -> JSON | INode[JSON, SUB_JSON, JSON]:
         children = self.build()
         names, sub_url = self.extract_child(children, url)
 
@@ -91,7 +91,7 @@ def _forward_get(
 
     def _expand_get(
         self, depth: int = -1, formatted: bool = True, get_node: bool = False
-    ) -> t.Union[JSON, INode[JSON, SUB_JSON, JSON]]:
+    ) -> JSON | INode[JSON, SUB_JSON, JSON]:
         if get_node:
             return self
 
@@ -110,7 +110,7 @@ def _get(
         depth: int = -1,
         formatted: bool = True,
         get_node: bool = False,
-    ) -> t.Union[JSON, INode[JSON, SUB_JSON, JSON]]:
+    ) -> JSON | INode[JSON, SUB_JSON, JSON]:
         if url and url != [""]:
             return self._forward_get(url, depth, formatted, get_node)
         else:
diff --git a/antarest/study/storage/rawstudy/model/filesystem/ini_file_node.py b/antarest/study/storage/rawstudy/model/filesystem/ini_file_node.py
index 960ccc83e4..099e3376d5 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/ini_file_node.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/ini_file_node.py
@@ -95,7 +95,7 @@ def _get(
         depth: int = -1,
         expanded: bool = False,
         get_node: bool = False,
-    ) -> t.Union[SUB_JSON, INode[SUB_JSON, SUB_JSON, JSON]]:
+    ) -> SUB_JSON | INode[SUB_JSON, SUB_JSON, JSON]:
         if get_node:
             return self
 
diff --git a/antarest/study/storage/rawstudy/model/filesystem/json_file_node.py b/antarest/study/storage/rawstudy/model/filesystem/json_file_node.py
index 0ff675c650..719b5ec1e8 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/json_file_node.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/json_file_node.py
@@ -32,7 +32,7 @@ class JsonReader(IReader):
 
     @override
     def read(self, path: t.Any, **kwargs: t.Any) -> JSON:
-        content: t.Union[str, bytes]
+        content: str | bytes
 
         if isinstance(path, (Path, str)):
             try:
diff --git a/antarest/study/storage/rawstudy/model/filesystem/lazy_node.py b/antarest/study/storage/rawstudy/model/filesystem/lazy_node.py
index 2a9204d71e..ba3a9c841b 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/lazy_node.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/lazy_node.py
@@ -76,7 +76,7 @@ def _get(
         expanded: bool = False,
         formatted: bool = True,
         get_node: bool = False,
-    ) -> t.Union[t.Union[str, G], INode[G, S, V]]:
+    ) -> str | G | INode[G, S, V]:
         self._assert_url_end(url)
 
         if get_node:
@@ -101,7 +101,7 @@ def get(
         depth: int = -1,
         expanded: bool = False,
         formatted: bool = True,
-    ) -> t.Union[str, G]:
+    ) -> str | G:
         output = self._get(url, depth, expanded, formatted, get_node=False)
         assert not isinstance(output, INode)
         return output
@@ -128,7 +128,7 @@ def get_link_path(self) -> Path:
         return path
 
     @override
-    def save(self, data: t.Union[str, bytes, S], url: t.Optional[t.List[str]] = None) -> None:
+    def save(self, data: str | bytes | S, url: t.Optional[t.List[str]] = None) -> None:
         self._assert_not_in_zipped_file()
         self._assert_url_end(url)
 
diff --git a/antarest/study/storage/rawstudy/model/filesystem/root/settings/scenariobuilder.py b/antarest/study/storage/rawstudy/model/filesystem/root/settings/scenariobuilder.py
index d384433216..69937ea4d2 100644
--- a/antarest/study/storage/rawstudy/model/filesystem/root/settings/scenariobuilder.py
+++ b/antarest/study/storage/rawstudy/model/filesystem/root/settings/scenariobuilder.py
@@ -29,7 +29,7 @@
 
 _TSNumber: te.TypeAlias = int
 _HydroLevel: te.TypeAlias = float
-_Rules = t.MutableMapping[str, t.Union[t.Type[_TSNumber], t.Type[_HydroLevel]]]
+_Rules = t.MutableMapping[str, t.Type[_TSNumber] | t.Type[_HydroLevel]]
 
 
 class ScenarioBuilder(IniFileNode):
diff --git a/antarest/study/storage/utils.py b/antarest/study/storage/utils.py
index e8336cc1d1..bd08ee76a4 100644
--- a/antarest/study/storage/utils.py
+++ b/antarest/study/storage/utils.py
@@ -214,7 +214,7 @@ def study_match(study: StudyMetadataDTO) -> bool:
 
 def assert_permission_on_studies(
     user: t.Optional[JWTUser],
-    studies: t.Sequence[t.Union[Study, StudyMetadataDTO]],
+    studies: t.Sequence[Study | StudyMetadataDTO],
     permission_type: StudyPermissionType,
     *,
     raising: bool = True,
@@ -254,7 +254,7 @@ def assert_permission_on_studies(
 
 def assert_permission(
     user: t.Optional[JWTUser],
-    study: t.Optional[t.Union[Study, StudyMetadataDTO]],
+    study: t.Optional[Study | StudyMetadataDTO],
     permission_type: StudyPermissionType,
     raising: bool = True,
 ) -> bool:
diff --git a/antarest/study/storage/variantstudy/business/utils.py b/antarest/study/storage/variantstudy/business/utils.py
index 84fb848056..eb82ddebb0 100644
--- a/antarest/study/storage/variantstudy/business/utils.py
+++ b/antarest/study/storage/variantstudy/business/utils.py
@@ -22,7 +22,7 @@
 from antarest.study.storage.variantstudy.model.model import CommandDTO
 
 
-def validate_matrix(matrix: t.Union[t.List[t.List[MatrixData]], str], values: t.Dict[str, t.Any]) -> str:
+def validate_matrix(matrix: t.List[t.List[MatrixData]] | str, values: t.Dict[str, t.Any]) -> str:
     """
     Validates the matrix, stores the matrix array in the matrices repository,
     and returns a reference to the stored array.
@@ -75,7 +75,7 @@ def remove_none_args(command_dto: CommandDTO) -> CommandDTO:
     return command_dto
 
 
-def strip_matrix_protocol(matrix_uri: t.Union[t.List[t.List[float]], str, None]) -> str:
+def strip_matrix_protocol(matrix_uri: t.List[t.List[float]] | str | None) -> str:
     assert isinstance(matrix_uri, str)
     if matrix_uri.startswith(MATRIX_PROTOCOL_PREFIX):
         return matrix_uri[len(MATRIX_PROTOCOL_PREFIX) :]
diff --git a/antarest/study/storage/variantstudy/business/utils_binding_constraint.py b/antarest/study/storage/variantstudy/business/utils_binding_constraint.py
index 399df46636..6c4d8c6eac 100644
--- a/antarest/study/storage/variantstudy/business/utils_binding_constraint.py
+++ b/antarest/study/storage/variantstudy/business/utils_binding_constraint.py
@@ -22,7 +22,7 @@
 def parse_bindings_coeffs_and_save_into_config(
     bd_id: str,
     study_data_config: FileStudyTreeConfig,
-    coeffs: t.Mapping[str, t.Union[t.Literal["hourly", "daily", "weekly"], t.Sequence[float]]],
+    coeffs: t.Mapping[str, t.Literal["hourly", "daily", "weekly"] | t.Sequence[float]],
     operator: BindingConstraintOperator,
     time_step: BindingConstraintFrequency,
     group: str,
diff --git a/antarest/study/storage/variantstudy/model/command/create_binding_constraint.py b/antarest/study/storage/variantstudy/model/command/create_binding_constraint.py
index 766934c8ee..02185483d8 100644
--- a/antarest/study/storage/variantstudy/model/command/create_binding_constraint.py
+++ b/antarest/study/storage/variantstudy/model/command/create_binding_constraint.py
@@ -122,11 +122,9 @@ class BindingConstraintProperties870(BindingConstraintProperties830):
     group: str = DEFAULT_GROUP
 
 
-BindingConstraintProperties = t.Union[
-    BindingConstraintPropertiesBase,
-    BindingConstraintProperties830,
-    BindingConstraintProperties870,
-]
+BindingConstraintProperties = (
+    BindingConstraintPropertiesBase | BindingConstraintProperties830 | BindingConstraintProperties870
+)
 
 
 def get_binding_constraint_config_cls(study_version: StudyVersion) -> t.Type[BindingConstraintProperties]:
@@ -173,27 +171,27 @@ class BindingConstraintMatrices(AntaresBaseModel, extra="forbid", populate_by_na
     Class used to store the matrices of a binding constraint.
     """
 
-    values: t.Optional[t.Union[MatrixType, str]] = Field(
+    values: t.Optional[MatrixType | str] = Field(
         default=None,
         description="2nd member matrix for studies before v8.7",
     )
-    less_term_matrix: t.Optional[t.Union[MatrixType, str]] = Field(
+    less_term_matrix: t.Optional[MatrixType | str] = Field(
         default=None,
         description="less term matrix for v8.7+ studies",
     )
-    greater_term_matrix: t.Optional[t.Union[MatrixType, str]] = Field(
+    greater_term_matrix: t.Optional[MatrixType | str] = Field(
         default=None,
         description="greater term matrix for v8.7+ studies",
     )
-    equal_term_matrix: t.Optional[t.Union[MatrixType, str]] = Field(
+    equal_term_matrix: t.Optional[MatrixType | str] = Field(
         default=None,
         description="equal term matrix for v8.7+ studies",
     )
 
     @model_validator(mode="before")
     def check_matrices(
-        cls, values: t.Dict[str, t.Optional[t.Union[MatrixType, str]]]
-    ) -> t.Dict[str, t.Optional[t.Union[MatrixType, str]]]:
+        cls, values: t.Dict[str, t.Optional[MatrixType | str]]
+    ) -> t.Dict[str, t.Optional[MatrixType | str]]:
         values_matrix = values.get("values") or None
         less_term_matrix = values.get("less_term_matrix") or None
         greater_term_matrix = values.get("greater_term_matrix") or None
@@ -263,7 +261,7 @@ def get_inner_matrices(self) -> t.List[str]:
 
     def get_corresponding_matrices(
         self,
-        v: t.Optional[t.Union[MatrixType, str]],
+        v: t.Optional[MatrixType | str],
         time_step: BindingConstraintFrequency,
         version: StudyVersion,
         create: bool,
diff --git a/antarest/study/storage/variantstudy/model/command/create_cluster.py b/antarest/study/storage/variantstudy/model/command/create_cluster.py
index c8f42fb60a..997fd2acf8 100644
--- a/antarest/study/storage/variantstudy/model/command/create_cluster.py
+++ b/antarest/study/storage/variantstudy/model/command/create_cluster.py
@@ -50,8 +50,8 @@ class CreateCluster(ICommand):
     area_id: str
     cluster_name: str
     parameters: t.Dict[str, t.Any]
-    prepro: t.Optional[t.Union[t.List[t.List[MatrixData]], str]] = Field(None, validate_default=True)
-    modulation: t.Optional[t.Union[t.List[t.List[MatrixData]], str]] = Field(None, validate_default=True)
+    prepro: t.Optional[t.List[t.List[MatrixData]] | str] = Field(None, validate_default=True)
+    modulation: t.Optional[t.List[t.List[MatrixData]] | str] = Field(None, validate_default=True)
 
     @field_validator("cluster_name", mode="before")
     def validate_cluster_name(cls, val: str) -> str:
@@ -63,9 +63,9 @@ def validate_cluster_name(cls, val: str) -> str:
     @field_validator("prepro", mode="before")
     def validate_prepro(
         cls,
-        v: t.Optional[t.Union[t.List[t.List[MatrixData]], str]],
-        values: t.Union[t.Dict[str, t.Any], ValidationInfo],
-    ) -> t.Optional[t.Union[t.List[t.List[MatrixData]], str]]:
+        v: t.Optional[t.List[t.List[MatrixData]] | str],
+        values: t.Dict[str, t.Any] | ValidationInfo,
+    ) -> t.Optional[t.List[t.List[MatrixData]] | str]:
         new_values = values if isinstance(values, dict) else values.data
         if v is None:
             v = new_values["command_context"].generator_matrix_constants.get_thermal_prepro_data()
@@ -76,9 +76,9 @@ def validate_prepro(
     @field_validator("modulation", mode="before")
     def validate_modulation(
         cls,
-        v: t.Optional[t.Union[t.List[t.List[MatrixData]], str]],
-        values: t.Union[t.Dict[str, t.Any], ValidationInfo],
-    ) -> t.Optional[t.Union[t.List[t.List[MatrixData]], str]]:
+        v: t.Optional[t.List[t.List[MatrixData]] | str],
+        values: t.Dict[str, t.Any] | ValidationInfo,
+    ) -> t.Optional[t.List[t.List[MatrixData]] | str]:
         new_values = values if isinstance(values, dict) else values.data
         if v is None:
             v = new_values["command_context"].generator_matrix_constants.get_thermal_prepro_modulation()
diff --git a/antarest/study/storage/variantstudy/model/command/create_st_storage.py b/antarest/study/storage/variantstudy/model/command/create_st_storage.py
index a3c16195ad..1ff12ec36c 100644
--- a/antarest/study/storage/variantstudy/model/command/create_st_storage.py
+++ b/antarest/study/storage/variantstudy/model/command/create_st_storage.py
@@ -61,23 +61,23 @@ class CreateSTStorage(ICommand):
 
     area_id: str = Field(description="Area ID", pattern=r"[a-z0-9_(),& -]+")
     parameters: STStorageConfigType
-    pmax_injection: t.Optional[t.Union[MatrixType, str]] = Field(
+    pmax_injection: t.Optional[MatrixType | str] = Field(
         default=None,
         description="Charge capacity (modulation)",
     )
-    pmax_withdrawal: t.Optional[t.Union[MatrixType, str]] = Field(
+    pmax_withdrawal: t.Optional[MatrixType | str] = Field(
         default=None,
         description="Discharge capacity (modulation)",
     )
-    lower_rule_curve: t.Optional[t.Union[MatrixType, str]] = Field(
+    lower_rule_curve: t.Optional[MatrixType | str] = Field(
         default=None,
         description="Lower rule curve (coefficient)",
     )
-    upper_rule_curve: t.Optional[t.Union[MatrixType, str]] = Field(
+    upper_rule_curve: t.Optional[MatrixType | str] = Field(
         default=None,
         description="Upper rule curve (coefficient)",
     )
-    inflows: t.Optional[t.Union[MatrixType, str]] = Field(
+    inflows: t.Optional[MatrixType | str] = Field(
         default=None,
         description="Inflows (MW)",
     )
@@ -94,8 +94,8 @@ def storage_name(self) -> str:
 
     @staticmethod
     def validate_field(
-        v: t.Optional[t.Union[MatrixType, str]], values: t.Dict[str, t.Any], field: str
-    ) -> t.Optional[t.Union[MatrixType, str]]:
+        v: t.Optional[MatrixType | str], values: t.Dict[str, t.Any], field: str
+    ) -> t.Optional[MatrixType | str]:
         """
         Validates a matrix array or link, and store the matrix array in the matrix repository.
 
@@ -155,7 +155,7 @@ def validate_field(
         raise TypeError(repr(v))
 
     @model_validator(mode="before")
-    def validate_matrices(cls, values: t.Union[t.Dict[str, t.Any], ValidationInfo]) -> t.Dict[str, t.Any]:
+    def validate_matrices(cls, values: t.Dict[str, t.Any] | ValidationInfo) -> t.Dict[str, t.Any]:
         new_values = values if isinstance(values, dict) else values.data
         for field in _MATRIX_NAMES:
             new_values[field] = cls.validate_field(new_values.get(field, None), new_values, field)
diff --git a/antarest/study/storage/variantstudy/model/command/replace_matrix.py b/antarest/study/storage/variantstudy/model/command/replace_matrix.py
index aaceb7c3f7..c51280bf8b 100644
--- a/antarest/study/storage/variantstudy/model/command/replace_matrix.py
+++ b/antarest/study/storage/variantstudy/model/command/replace_matrix.py
@@ -44,10 +44,10 @@ class ReplaceMatrix(ICommand):
     # ==================
 
     target: str
-    matrix: t.Union[t.List[t.List[MatrixData]], str] = Field(validate_default=True)
+    matrix: t.List[t.List[MatrixData]] | str = Field(validate_default=True)
 
     @field_validator("matrix", mode="before")
-    def matrix_validator(cls, matrix: t.Union[t.List[t.List[MatrixData]], str], values: ValidationInfo) -> str:
+    def matrix_validator(cls, matrix: t.List[t.List[MatrixData]] | str, values: ValidationInfo) -> str:
         return validate_matrix(matrix, values.data)
 
     @override
diff --git a/antarest/study/storage/variantstudy/model/command/update_config.py b/antarest/study/storage/variantstudy/model/command/update_config.py
index e53ed7edfe..159cd535dd 100644
--- a/antarest/study/storage/variantstudy/model/command/update_config.py
+++ b/antarest/study/storage/variantstudy/model/command/update_config.py
@@ -26,7 +26,7 @@
 
 _ENR_MODELLING_KEY = "settings/generaldata/other preferences/renewable-generation-modelling"
 
-_Data: te.TypeAlias = t.Union[str, int, float, bool, JSON, None]
+_Data: te.TypeAlias = str | int | float | bool | JSON | None
 
 
 def _iter_dict(data: _Data, root_key: str = "") -> t.Generator[t.Tuple[str, t.Any], None, None]:
diff --git a/antarest/study/storage/variantstudy/model/command/update_scenario_builder.py b/antarest/study/storage/variantstudy/model/command/update_scenario_builder.py
index 6ae373e238..3180e78fce 100644
--- a/antarest/study/storage/variantstudy/model/command/update_scenario_builder.py
+++ b/antarest/study/storage/variantstudy/model/command/update_scenario_builder.py
@@ -53,7 +53,7 @@ class UpdateScenarioBuilder(ICommand):
     # Command parameters
     # ==================
 
-    data: t.Union[t.Dict[str, t.Any], t.Mapping[str, t.Any], t.MutableMapping[str, t.Any]]
+    data: t.Dict[str, t.Any] | t.Mapping[str, t.Any] | t.MutableMapping[str, t.Any]
 
     @override
     def _apply(self, study_data: FileStudy, listener: t.Optional[ICommandListener] = None) -> CommandOutput:
diff --git a/antarest/study/storage/variantstudy/model/model.py b/antarest/study/storage/variantstudy/model/model.py
index cb1866037f..a9c24f4ff9 100644
--- a/antarest/study/storage/variantstudy/model/model.py
+++ b/antarest/study/storage/variantstudy/model/model.py
@@ -42,7 +42,7 @@ class NewDetailsDTO(te.TypedDict):
     msg: str
 
 
-DetailsDTO = t.Union[LegacyDetailsDTO, NewDetailsDTO]
+DetailsDTO = LegacyDetailsDTO | NewDetailsDTO
 
 
 class GenerationResultInfoDTO(AntaresBaseModel):
@@ -71,7 +71,7 @@ class CommandDTOAPI(AntaresBaseModel):
 
     id: t.Optional[str] = None
     action: str
-    args: t.Union[t.MutableSequence[JSON], JSON]
+    args: t.MutableSequence[JSON] | JSON
     version: int = 1
     user_name: t.Optional[str] = None
     updated_at: t.Optional[datetime.datetime] = None
@@ -93,7 +93,7 @@ class CommandDTO(AntaresBaseModel):
 
     id: t.Optional[str] = None
     action: str
-    args: t.Union[t.MutableSequence[JSON], JSON]
+    args: t.MutableSequence[JSON] | JSON
     version: int = 1
     study_version: StudyVersionStr
     user_id: t.Optional[int] = None
diff --git a/antarest/study/storage/variantstudy/snapshot_generator.py b/antarest/study/storage/variantstudy/snapshot_generator.py
index 58d4d62b7b..901db0f54c 100644
--- a/antarest/study/storage/variantstudy/snapshot_generator.py
+++ b/antarest/study/storage/variantstudy/snapshot_generator.py
@@ -151,7 +151,7 @@ def _retrieve_descendants(self, variant_study_id: str) -> t.Tuple[RawStudy, t.Se
         root_study = self.repository.one(descendant_ids[0])
         return root_study, descendants
 
-    def _export_ref_study(self, snapshot_dir: Path, ref_study: t.Union[RawStudy, VariantStudy]) -> None:
+    def _export_ref_study(self, snapshot_dir: Path, ref_study: RawStudy | VariantStudy) -> None:
         if isinstance(ref_study, VariantStudy):
             snapshot_dir.parent.mkdir(parents=True, exist_ok=True)
             export_study_flat(
@@ -224,13 +224,13 @@ class RefStudySearchResult(t.NamedTuple):
     Result of the search for the reference study.
     """
 
-    ref_study: t.Union[RawStudy, VariantStudy]
+    ref_study: RawStudy | VariantStudy
     cmd_blocks: t.Sequence[CommandBlock]
     force_regenerate: bool = False
 
 
 def search_ref_study(
-    root_study: t.Union[RawStudy, VariantStudy],
+    root_study: RawStudy | VariantStudy,
     descendants: t.Sequence[VariantStudy],
     *,
     from_scratch: bool = False,
@@ -251,7 +251,7 @@ def search_ref_study(
         return RefStudySearchResult(ref_study=root_study, cmd_blocks=[], force_regenerate=True)
 
     # The reference study is the root study or a variant study with a valid snapshot
-    ref_study: t.Union[RawStudy, VariantStudy]
+    ref_study: RawStudy | VariantStudy
 
     # The commands to apply on the reference study to generate the current variant
     cmd_blocks: t.List[CommandBlock]
diff --git a/antarest/study/storage/variantstudy/variant_study_service.py b/antarest/study/storage/variantstudy/variant_study_service.py
index ba865f5d12..a8b1db25fc 100644
--- a/antarest/study/storage/variantstudy/variant_study_service.py
+++ b/antarest/study/storage/variantstudy/variant_study_service.py
@@ -1206,8 +1206,8 @@ def _clear_all_snapshots(self) -> None:
                 )
             )
             for variant in variant_list:
-                if variant.updated_at and variant.updated_at < datetime.now(timezone.utc) - self._retention_time:
-                    if variant.last_access and variant.last_access < datetime.now(timezone.utc) - self._retention_time:
+                if variant.updated_at and variant.updated_at < datetime.utcnow() - self._retention_time:
+                    if variant.last_access and variant.last_access < datetime.utcnow() - self._retention_time:
                         self._variant_study_service.clear_snapshot(variant)
 
     def run_task(self, notifier: ITaskNotifier) -> TaskResult:
diff --git a/antarest/study/web/study_data_blueprint.py b/antarest/study/web/study_data_blueprint.py
index 95659ecd7f..23a7ded9ab 100644
--- a/antarest/study/web/study_data_blueprint.py
+++ b/antarest/study/web/study_data_blueprint.py
@@ -91,7 +91,7 @@ class BCKeyValueType(te.TypedDict):
     """Deprecated type for binding constraint key-value pair (used for update)"""
 
     key: str
-    value: t.Union[str, int, float, bool]
+    value: str | int | float | bool
 
 
 class ClusterType(enum.StrEnum):
@@ -127,14 +127,14 @@ def create_study_data_routes(study_service: StudyService, config: Config) -> API
         "/studies/{uuid}/areas",
         tags=[APITag.study_data],
         summary="Get all areas basic info",
-        response_model=t.Union[t.List[AreaInfoDTO], t.Dict[str, t.Any]],
+        response_model=t.List[AreaInfoDTO] | t.Dict[str, t.Any],
     )
     def get_areas(
         uuid: str,
         type: AreaType = Query(None),
         ui: bool = False,
         current_user: JWTUser = Depends(auth.get_current_user),
-    ) -> t.Union[t.List[AreaInfoDTO], t.Dict[str, t.Any]]:
+    ) -> t.List[AreaInfoDTO] | t.Dict[str, t.Any]:
         logger.info(
             f"Fetching area list (type={type}) for study {uuid}",
             extra={"user": current_user.id},
@@ -246,7 +246,7 @@ def update_area_ui(
     def update_area_info(
         uuid: str,
         area_id: str,
-        area_patch_dto: t.Union[PatchArea, t.Dict[str, PatchCluster]],
+        area_patch_dto: PatchArea | t.Dict[str, PatchCluster],
         current_user: JWTUser = Depends(auth.get_current_user),
     ) -> t.Any:
         logger.info(
@@ -2599,7 +2599,7 @@ def duplicate_cluster(
         source_cluster_id: str,
         new_cluster_name: str = Query(..., alias="newName", title="New Cluster Name"),
         current_user: JWTUser = Depends(auth.get_current_user),
-    ) -> t.Union[STStorageOutput, ThermalClusterOutput, RenewableClusterOutput]:
+    ) -> STStorageOutput | ThermalClusterOutput | RenewableClusterOutput:
         logger.info(
             f"Duplicates {cluster_type.value} {source_cluster_id} of {area_id} for study {uuid}",
             extra={"user": current_user.id},
@@ -2607,7 +2607,7 @@ def duplicate_cluster(
         params = RequestParameters(user=current_user)
         study = study_service.check_study_access(uuid, StudyPermissionType.WRITE, params)
 
-        manager: t.Union[STStorageManager, RenewableManager, ThermalManager]
+        manager: STStorageManager | RenewableManager | ThermalManager
         if cluster_type == ClusterType.ST_STORAGES:
             manager = STStorageManager(study_service.storage_service)
         elif cluster_type == ClusterType.RENEWABLES:
diff --git a/antarest/study/web/xpansion_studies_blueprint.py b/antarest/study/web/xpansion_studies_blueprint.py
index 0871efd0f0..dcdc88dbf9 100644
--- a/antarest/study/web/xpansion_studies_blueprint.py
+++ b/antarest/study/web/xpansion_studies_blueprint.py
@@ -271,9 +271,7 @@ def get_resource_content(
             StudyPermissionType.READ,
             RequestParameters(user=current_user),
         )
-        output: t.Union[JSON, bytes, str] = study_service.xpansion_manager.get_resource_content(
-            study, resource_type, filename
-        )
+        output: JSON | bytes | str = study_service.xpansion_manager.get_resource_content(study, resource_type, filename)
 
         if isinstance(output, bytes):
             try:
diff --git a/tests/integration/study_data_blueprint/test_link.py b/tests/integration/study_data_blueprint/test_link.py
index 7ba267c7cd..9585ad674d 100644
--- a/tests/integration/study_data_blueprint/test_link.py
+++ b/tests/integration/study_data_blueprint/test_link.py
@@ -9,6 +9,8 @@
 # SPDX-License-Identifier: MPL-2.0
 #
 # This file is part of the Antares project.
+import re
+
 import pytest
 from starlette.testclient import TestClient
 
@@ -284,11 +286,14 @@ def test_link_820(self, client: TestClient, user_access_token: str, study_type:
         )
 
         assert res.status_code == 422, res.json()
-        expected = {
-            "description": "Invalid value(s) in filters: centurial. Allowed values are: hourly, daily, weekly, monthly, annual.",
-            "exception": "LinkValidationError",
-        }
-        assert expected == res.json()
+
+        res_json = res.json()
+        assert res_json["exception"] == "LinkValidationError"
+        match = re.search(r"Allowed values are: (.*)\.", res_json["description"])
+        assert match, f"Unexpected error message format: {res_json['description']}"
+        res_values = sorted(match.group(1).split(", "))
+        expected_values = sorted(["daily", "hourly", "monthly", "weekly", "annual"])
+        assert res_values == expected_values, f"Returned values: {res_values}, expected: {expected_values}"
 
         # Test create link with empty filters