diff --git a/src/lib/error/api-error.test.ts b/src/lib/error/api-error.test.ts
index 7e1cae4039..8077246fd8 100644
--- a/src/lib/error/api-error.test.ts
+++ b/src/lib/error/api-error.test.ts
@@ -1,9 +1,47 @@
 import { ErrorObject } from 'ajv';
 import {
     ApiErrorSchema,
+    fromLegacyError,
     fromOpenApiValidationError,
     fromOpenApiValidationErrors,
+    UnleashApiErrorNameWithoutExtraData,
+    UnleashApiErrorTypes,
+    UnleashError,
 } from './api-error';
+import BadDataError from './bad-data-error';
+
+describe('v5 deprecation: backwards compatibility', () => {
+    it.each(UnleashApiErrorTypes)(
+        'Adds details to error type: "%s"',
+        (name: UnleashApiErrorNameWithoutExtraData) => {
+            const message = `Error type: ${name}`;
+            const error = new UnleashError({ name, message }).toJSON();
+
+            expect(error.message).toBe(message);
+            expect(error.details).toStrictEqual([
+                {
+                    message,
+                    description: message,
+                },
+            ]);
+        },
+    );
+});
+
+describe('Standard/legacy error conversion', () => {
+    it('Moves message to the details list for baddataerror', () => {
+        const message = `: message!`;
+        const result = fromLegacyError(new BadDataError(message)).toJSON();
+
+        expect(result.message.includes('`details`'));
+        expect(result.details).toStrictEqual([
+            {
+                message,
+                description: message,
+            },
+        ]);
+    });
+});
 
 describe('OpenAPI error conversion', () => {
     it('Gives useful error messages for missing properties', () => {
diff --git a/src/lib/error/api-error.ts b/src/lib/error/api-error.ts
index cdaff9c42c..70fa805118 100644
--- a/src/lib/error/api-error.ts
+++ b/src/lib/error/api-error.ts
@@ -2,32 +2,32 @@ import { v4 as uuidV4 } from 'uuid';
 import { FromSchema } from 'json-schema-to-ts';
 import { ErrorObject } from 'ajv';
 
-const UnleashApiErrorTypes = [
-    'OwaspValidationError',
-    'PasswordUndefinedError',
-    'NoAccessError',
-    'UsedTokenError',
-    'InvalidOperationError',
-    'IncompatibleProjectError',
-    'OperationDeniedError',
-    'NotFoundError',
-    'NameExistsError',
+export const UnleashApiErrorTypes = [
+    'ContentTypeError',
+    'DisabledError',
     'FeatureHasTagError',
-    'RoleInUseError',
-    'ProjectWithoutOwnerError',
-    'UnknownError',
+    'IncompatibleProjectError',
+    'InvalidOperationError',
+    'MinimumOneEnvironmentError',
+    'NameExistsError',
+    'NoAccessError',
+    'NotFoundError',
+    'NotImplementedError',
+    'OperationDeniedError',
+    'OwaspValidationError',
     'PasswordMismatch',
     'PasswordMismatchError',
-    'DisabledError',
-    'ContentTypeError',
-    'NotImplementedError',
+    'PasswordUndefinedError',
+    'ProjectWithoutOwnerError',
+    'RoleInUseError',
+    'UnknownError',
+    'UsedTokenError',
 
     // server errors; not the end user's fault
     'InternalError',
 ] as const;
 
 const UnleashApiErrorTypesWithExtraData = [
-    'MinimumOneEnvironmentError',
     'BadDataError',
     'BadRequestError',
     'ValidationError',
@@ -42,10 +42,8 @@ const AllUnleashApiErrorTypes = [
 ] as const;
 
 type UnleashApiErrorName = typeof AllUnleashApiErrorTypes[number];
-type UnleashApiErrorNameWithoutExtraData = Exclude<
-    UnleashApiErrorName,
-    typeof UnleashApiErrorTypesWithExtraData[number]
->;
+export type UnleashApiErrorNameWithoutExtraData =
+    typeof UnleashApiErrorTypes[number];
 
 const statusCode = (errorName: UnleashApiErrorName): number => {
     switch (errorName) {
@@ -174,6 +172,7 @@ export class UnleashError extends Error {
             id: this.id,
             name: this.name,
             message: this.message,
+            details: [{ message: this.message, description: this.message }],
             ...this.additionalParameters,
         };
     }
@@ -228,11 +227,10 @@ export const fromLegacyError = (e: Error): UnleashError => {
 
     if (
         [
-            'ValidationError',
-            'BadRequestError',
             'BadDataError',
+            'BadRequestError',
             'InvalidTokenError',
-            'MinimumOneEnvironmentError',
+            'ValidationError',
         ].includes(name)
     ) {
         return new UnleashError({
@@ -240,10 +238,9 @@ export const fromLegacyError = (e: Error): UnleashError => {
                 | 'ValidationError'
                 | 'BadRequestError'
                 | 'BadDataError'
-                | 'InvalidTokenError'
-                | 'MinimumOneEnvironmentError',
+                | 'InvalidTokenError',
             message:
-                'Your request body failed to validate. Refer to the `details` list to see what happened.',
+                'Request validation failed: your request body failed to validate. Refer to the `details` list to see what happened.',
             details: [{ description: e.message, message: e.message }],
         });
     }
diff --git a/src/lib/routes/util.ts b/src/lib/routes/util.ts
index 078c6d89e9..3a262c7e80 100644
--- a/src/lib/routes/util.ts
+++ b/src/lib/routes/util.ts
@@ -26,14 +26,11 @@ export const handleErrors: (
     logger: Logger,
     error: Error,
 ) => void = (res, logger, error) => {
-    logger.warn(error.message);
-    // @ts-expect-error
-    // eslint-disable-next-line no-param-reassign
-    error.isJoi = true;
-
     const finalError =
         error instanceof UnleashError ? error : fromLegacyError(error);
 
+    logger.warn(finalError.id, finalError.message);
+
     if (['InternalError', 'UnknownError'].includes(finalError.name)) {
         logger.error('Server failed executing request', error);
     }