diff --git a/packages/twenty-server/src/engine/api/graphql/workspace-query-runner/utils/workspace-query-runner-graphql-api-exception-handler.util.ts b/packages/twenty-server/src/engine/api/graphql/workspace-query-runner/utils/workspace-query-runner-graphql-api-exception-handler.util.ts
index 4b25b71d6c..d5a0ffed7b 100644
--- a/packages/twenty-server/src/engine/api/graphql/workspace-query-runner/utils/workspace-query-runner-graphql-api-exception-handler.util.ts
+++ b/packages/twenty-server/src/engine/api/graphql/workspace-query-runner/utils/workspace-query-runner-graphql-api-exception-handler.util.ts
@@ -20,6 +20,8 @@ import { PermissionsException } from 'src/engine/metadata-modules/permissions/pe
 import { permissionGraphqlApiExceptionHandler } from 'src/engine/metadata-modules/permissions/utils/permission-graphql-api-exception-handler.util';
 import { TwentyORMException } from 'src/engine/twenty-orm/exceptions/twenty-orm.exception';
 import { twentyORMGraphqlApiExceptionHandler } from 'src/engine/twenty-orm/utils/twenty-orm-graphql-api-exception-handler.util';
+import { WorkflowQueryValidationException } from 'src/modules/workflow/common/exceptions/workflow-query-validation.exception';
+import { workflowQueryValidationGraphqlApiExceptionHandler } from 'src/modules/workflow/common/utils/workflow-query-validation-graphql-api-exception-handler.util';
 
 interface QueryFailedErrorWithCode extends QueryFailedError {
   code: string;
@@ -49,6 +51,8 @@ export const workspaceQueryRunnerGraphqlApiExceptionHandler = (
       return throttlerToGraphqlApiExceptionHandler(error);
     case error instanceof GraphqlDirectExecutionException:
       return graphqlDirectExecutionToGraphqlApiExceptionHandler(error);
+    case error instanceof WorkflowQueryValidationException:
+      return workflowQueryValidationGraphqlApiExceptionHandler(error);
     default:
       throw error;
   }
diff --git a/packages/twenty-server/src/modules/workflow/common/utils/workflow-query-validation-graphql-api-exception-handler.util.ts b/packages/twenty-server/src/modules/workflow/common/utils/workflow-query-validation-graphql-api-exception-handler.util.ts
new file mode 100644
index 0000000000..df57364c04
--- /dev/null
+++ b/packages/twenty-server/src/modules/workflow/common/utils/workflow-query-validation-graphql-api-exception-handler.util.ts
@@ -0,0 +1,19 @@
+import { assertUnreachable } from 'twenty-shared/utils';
+
+import { ForbiddenError } from 'src/engine/core-modules/graphql/utils/graphql-errors.util';
+import {
+  type WorkflowQueryValidationException,
+  WorkflowQueryValidationExceptionCode,
+} from 'src/modules/workflow/common/exceptions/workflow-query-validation.exception';
+
+export const workflowQueryValidationGraphqlApiExceptionHandler = (
+  exception: WorkflowQueryValidationException,
+) => {
+  switch (exception.code) {
+    case WorkflowQueryValidationExceptionCode.FORBIDDEN:
+      throw new ForbiddenError(exception);
+    default: {
+      assertUnreachable(exception.code);
+    }
+  }
+};
diff --git a/packages/twenty-server/src/modules/workflow/workflow-executor/workflow-actions/iterator/iterator.workflow-action.ts b/packages/twenty-server/src/modules/workflow/workflow-executor/workflow-actions/iterator/iterator.workflow-action.ts
index 8a49c86d95..07d17f0b45 100644
--- a/packages/twenty-server/src/modules/workflow/workflow-executor/workflow-actions/iterator/iterator.workflow-action.ts
+++ b/packages/twenty-server/src/modules/workflow/workflow-executor/workflow-actions/iterator/iterator.workflow-action.ts
@@ -55,7 +55,7 @@ export class IteratorWorkflowAction implements WorkflowActionInterface {
     if (!Array.isArray(parsedItems)) {
       throw new WorkflowStepExecutorException(
         'Iterator input items must be an array',
-        WorkflowStepExecutorExceptionCode.INTERNAL_ERROR,
+        WorkflowStepExecutorExceptionCode.INVALID_STEP_INPUT,
       );
     }