diff --git a/src/Squidex/Areas/Api/Config/Swagger/ErrorDtoProcessor.cs b/src/Squidex/Areas/Api/Config/Swagger/ErrorDtoProcessor.cs
new file mode 100644
index 000000000..f04099cb5
--- /dev/null
+++ b/src/Squidex/Areas/Api/Config/Swagger/ErrorDtoProcessor.cs
@@ -0,0 +1,70 @@
+// ==========================================================================
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex UG (haftungsbeschraenkt)
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using NJsonSchema;
+using NSwag;
+using NSwag.SwaggerGeneration.Processors;
+using NSwag.SwaggerGeneration.Processors.Contexts;
+using Squidex.ClientLibrary.Management;
+using Squidex.Pipeline.Swagger;
+
+namespace Squidex.Areas.Api.Config.Swagger
+{
+    public sealed class ErrorDtoProcessor : IDocumentProcessor
+    {
+        public async Task ProcessAsync(DocumentProcessorContext context)
+        {
+            var errorSchema = await GetErrorSchemaAsync(context);
+
+            foreach (var operation in context.Document.Paths.Values.SelectMany(x => x.Values))
+            {
+                AddErrorResponses(operation, errorSchema);
+
+                CleanupResponses(operation);
+            }
+        }
+
+        private static void AddErrorResponses(SwaggerOperation operation, JsonSchema4 errorSchema)
+        {
+            if (!operation.Responses.ContainsKey("500"))
+            {
+                operation.AddResponse("500", "Operation failed", errorSchema);
+            }
+
+            foreach (var (code, response) in operation.Responses)
+            {
+                if (code != "404" && code.StartsWith("4", StringComparison.OrdinalIgnoreCase) && response.Schema == null)
+                {
+                    response.Schema = errorSchema;
+                }
+            }
+        }
+
+        private static void CleanupResponses(SwaggerOperation operation)
+        {
+            foreach (var (code, response) in operation.Responses.ToList())
+            {
+                if (string.IsNullOrWhiteSpace(response.Description) ||
+                    response.Description?.Contains("=>") == true ||
+                    response.Description?.Contains("=>") == true)
+                {
+                    operation.Responses.Remove(code);
+                }
+            }
+        }
+
+        private Task<JsonSchema4> GetErrorSchemaAsync(DocumentProcessorContext context)
+        {
+            var errorType = typeof(ErrorDto);
+
+            return context.SchemaGenerator.GenerateWithReferenceAsync<JsonSchema4>(errorType, Enumerable.Empty<Attribute>(), context.SchemaResolver);
+        }
+    }
+}
diff --git a/src/Squidex/app/framework/utils/error.ts b/src/Squidex/app/framework/utils/error.ts
index 72bac2567..48c1c8413 100644
--- a/src/Squidex/app/framework/utils/error.ts
+++ b/src/Squidex/app/framework/utils/error.ts
@@ -15,6 +15,10 @@ export class ErrorDto {
     ) {
         this.displayMessage = formatMessage(message, details);
     }
+
+    public toString() {
+        return `ErrorDto(${JSON.stringify(this)})`;
+    }
 }