diff --git a/core/src/main/java/org/mobilitydata/gtfsvalidator/notice/MalformedJsonNotice.java b/core/src/main/java/org/mobilitydata/gtfsvalidator/notice/MalformedJsonNotice.java
index 6c4591ad17..c958b2e4d6 100644
--- a/core/src/main/java/org/mobilitydata/gtfsvalidator/notice/MalformedJsonNotice.java
+++ b/core/src/main/java/org/mobilitydata/gtfsvalidator/notice/MalformedJsonNotice.java
@@ -26,7 +26,11 @@ public class MalformedJsonNotice extends ValidationNotice {
   /** The name of the faulty file. */
   private final String filename;
 
-  public MalformedJsonNotice(String filename) {
+  /** The detailed message describing the error. */
+  private final String message;
+
+  public MalformedJsonNotice(String filename, String message) {
     this.filename = filename;
+    this.message = message;
   }
 }
diff --git a/core/src/main/java/org/mobilitydata/gtfsvalidator/notice/UnsupportedGeoJsonTypeNotice.java b/core/src/main/java/org/mobilitydata/gtfsvalidator/notice/UnsupportedGeoJsonTypeNotice.java
index e75482c293..1c81ac3379 100644
--- a/core/src/main/java/org/mobilitydata/gtfsvalidator/notice/UnsupportedGeoJsonTypeNotice.java
+++ b/core/src/main/java/org/mobilitydata/gtfsvalidator/notice/UnsupportedGeoJsonTypeNotice.java
@@ -30,7 +30,11 @@ public class UnsupportedGeoJsonTypeNotice extends ValidationNotice {
   /** The value of the unsupported GeoJSON type. */
   private final String geoJsonType;
 
-  public UnsupportedGeoJsonTypeNotice(String geoJsonType) {
+  /** The detailed message describing the error. */
+  private final String message;
+
+  public UnsupportedGeoJsonTypeNotice(String geoJsonType, String message) {
     this.geoJsonType = geoJsonType;
+    this.message = message;
   }
 }
diff --git a/main/src/main/java/org/mobilitydata/gtfsvalidator/table/GeoJsonFileLoader.java b/main/src/main/java/org/mobilitydata/gtfsvalidator/table/GeoJsonFileLoader.java
index db9bc81aa4..9e6f4960ff 100644
--- a/main/src/main/java/org/mobilitydata/gtfsvalidator/table/GeoJsonFileLoader.java
+++ b/main/src/main/java/org/mobilitydata/gtfsvalidator/table/GeoJsonFileLoader.java
@@ -40,7 +40,8 @@ public GtfsEntityContainer load(
       List<GtfsGeoJsonFeature> entities = extractFeaturesFromStream(inputStream, noticeContainer);
       return geoJsonFileDescriptor.createContainerForEntities(entities, noticeContainer);
     } catch (JsonParseException jpex) {
-      noticeContainer.addValidationNotice(new MalformedJsonNotice(GtfsGeoJsonFeature.FILENAME));
+      noticeContainer.addValidationNotice(
+          new MalformedJsonNotice(GtfsGeoJsonFeature.FILENAME, jpex.getMessage()));
       logger.atSevere().withCause(jpex).log("Malformed JSON in locations.geojson");
       return fileDescriptor.createContainerForInvalidStatus(TableStatus.UNPARSABLE_ROWS);
     } catch (IOException ioex) {
@@ -55,6 +56,15 @@ public GtfsEntityContainer load(
     }
   }
 
+  /**
+   * Extracts features from the provided GeoJSON input stream.
+   *
+   * @param inputStream the input stream containing GeoJSON data
+   * @param noticeContainer the container to collect validation notices
+   * @return a list of parsed GeoJSON features
+   * @throws IOException if an I/O error occurs while reading the input stream
+   * @throws UnparsableGeoJsonFeatureException if any GeoJSON feature is unparsable
+   */
   public List<GtfsGeoJsonFeature> extractFeaturesFromStream(
       InputStream inputStream, NoticeContainer noticeContainer)
       throws IOException, UnparsableGeoJsonFeatureException {
@@ -67,7 +77,11 @@ public List<GtfsGeoJsonFeature> extractFeaturesFromStream(
         throw new UnparsableGeoJsonFeatureException("Missing required field 'type'");
       } else if (!jsonObject.get("type").getAsString().equals("FeatureCollection")) {
         noticeContainer.addValidationNotice(
-            new UnsupportedGeoJsonTypeNotice(jsonObject.get("type").getAsString()));
+            new UnsupportedGeoJsonTypeNotice(
+                jsonObject.get("type").getAsString(),
+                "Unsupported GeoJSON type: "
+                    + jsonObject.get("type").getAsString()
+                    + ". Use 'FeatureCollection' instead."));
         throw new UnparsableGeoJsonFeatureException("Unsupported GeoJSON type");
       }
       JsonArray featuresArray = jsonObject.getAsJsonArray("features");