From 49acf677091ef0533ac79679418d3fbcbc4284d3 Mon Sep 17 00:00:00 2001
From: Andy Butland <abutland73@gmail.com>
Date: Fri, 24 Oct 2025 08:14:10 +0200
Subject: [PATCH 1/2] Handle null configured file extensions when populating
 allowed media types.

---
 .../Services/ContentTypeEditing/MediaTypeEditingService.cs      | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Umbraco.Core/Services/ContentTypeEditing/MediaTypeEditingService.cs b/src/Umbraco.Core/Services/ContentTypeEditing/MediaTypeEditingService.cs
index 8a626215b4ea..9d69ae483d8d 100644
--- a/src/Umbraco.Core/Services/ContentTypeEditing/MediaTypeEditingService.cs
+++ b/src/Umbraco.Core/Services/ContentTypeEditing/MediaTypeEditingService.cs
@@ -175,7 +175,7 @@ private async Task<IDictionary<IMediaType, IEnumerable<string>>> FetchAllowedFil
                 continue;
             }
 
-            allowedFileExtensionsByMediaType[mediaType] = fileUploadConfiguration.FileExtensions;
+            allowedFileExtensionsByMediaType[mediaType] = fileUploadConfiguration.FileExtensions ?? [];
         }
 
         return allowedFileExtensionsByMediaType;

From 922bfc8675f8b9ac94dbc25aac2c3e3b93a1e5aa Mon Sep 17 00:00:00 2001
From: Andy Butland <abutland73@gmail.com>
Date: Fri, 24 Oct 2025 08:32:43 +0200
Subject: [PATCH 2/2] Added clarifying comment.

---
 .../Services/ContentTypeEditing/MediaTypeEditingService.cs      | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Umbraco.Core/Services/ContentTypeEditing/MediaTypeEditingService.cs b/src/Umbraco.Core/Services/ContentTypeEditing/MediaTypeEditingService.cs
index 9d69ae483d8d..4955eeec9cd1 100644
--- a/src/Umbraco.Core/Services/ContentTypeEditing/MediaTypeEditingService.cs
+++ b/src/Umbraco.Core/Services/ContentTypeEditing/MediaTypeEditingService.cs
@@ -175,7 +175,7 @@ private async Task<IDictionary<IMediaType, IEnumerable<string>>> FetchAllowedFil
                 continue;
             }
 
-            allowedFileExtensionsByMediaType[mediaType] = fileUploadConfiguration.FileExtensions ?? [];
+            allowedFileExtensionsByMediaType[mediaType] = fileUploadConfiguration.FileExtensions ?? []; // Although we never expect null here, legacy data type configuration did allow it.
         }
 
         return allowedFileExtensionsByMediaType;