diff --git a/src/lib/error/api-error.test.ts b/src/lib/error/api-error.test.ts
index 8077246fd8..ed52fce940 100644
--- a/src/lib/error/api-error.test.ts
+++ b/src/lib/error/api-error.test.ts
@@ -1,3 +1,4 @@
+import owasp from 'owasp-password-strength-test';
 import { ErrorObject } from 'ajv';
 import {
     ApiErrorSchema,
@@ -9,6 +10,7 @@ import {
     UnleashError,
 } from './api-error';
 import BadDataError from './bad-data-error';
+import OwaspValidationError from './owasp-validation-error';
 
 describe('v5 deprecation: backwards compatibility', () => {
     it.each(UnleashApiErrorTypes)(
@@ -320,3 +322,14 @@ describe('OpenAPI error conversion', () => {
         expect(description.includes(illegalValue)).toBeTruthy();
     });
 });
+
+describe('Error serialization special cases', () => {
+    it('OwaspValidationErrors: adds `validationErrors` to `details`', () => {
+        const results = owasp.test('123');
+        const error = new OwaspValidationError(results);
+        const json = fromLegacyError(error).toJSON();
+
+        expect(json.details!![0].message).toBe(results.errors[0]);
+        expect(json.details!![0].validationErrors).toBe(results.errors);
+    });
+});
diff --git a/src/lib/error/api-error.ts b/src/lib/error/api-error.ts
index 70fa805118..028c1307ac 100644
--- a/src/lib/error/api-error.ts
+++ b/src/lib/error/api-error.ts
@@ -1,6 +1,7 @@
 import { v4 as uuidV4 } from 'uuid';
 import { FromSchema } from 'json-schema-to-ts';
 import { ErrorObject } from 'ajv';
+import OwaspValidationError from './owasp-validation-error';
 
 export const UnleashApiErrorTypes = [
     'ContentTypeError',
@@ -14,7 +15,6 @@ export const UnleashApiErrorTypes = [
     'NotFoundError',
     'NotImplementedError',
     'OperationDeniedError',
-    'OwaspValidationError',
     'PasswordMismatch',
     'PasswordMismatchError',
     'PasswordUndefinedError',
@@ -34,6 +34,7 @@ const UnleashApiErrorTypesWithExtraData = [
     'AuthenticationRequired',
     'NoAccessError',
     'InvalidTokenError',
+    'OwaspValidationError',
 ] as const;
 
 const AllUnleashApiErrorTypes = [
@@ -136,6 +137,15 @@ type UnleashErrorData =
                     ...ValidationErrorDescription[],
                 ];
             }
+          | {
+                name: 'OwaspValidationError';
+                details: [
+                    {
+                        validationErrors: string[];
+                        message: string;
+                    },
+                ];
+            }
       );
 
 export class UnleashError extends Error {
@@ -245,6 +255,15 @@ export const fromLegacyError = (e: Error): UnleashError => {
         });
     }
 
+    if (name === 'OwaspValidationError') {
+        return new UnleashError({
+            name,
+            message:
+                'Password validation failed. Refer to the `details` property.',
+            details: (e as OwaspValidationError).toJSON().details,
+        });
+    }
+
     if (name === 'AuthenticationRequired') {
         return new UnleashError({
             name,