Blank Page on /u/login* in Auth0

Last Updated: Jul 7, 2026

Overview

This article explains how to resolve an issue causing a blank page on /u/login* when testing with a custom domain.

Network traffic on /u/login* shows the script or stylesheet calls returning 404s like this: https://<CUSTOM-DOMAIN>/u/login/<ASSET_URL>

Applies To

Auth0
New Universal Login with Custom Domain
Page Template
Advanced Customizations for Universal Login (ACUL) Advanced Rendering Mode

Cause

The ACUL advanced rendering mode feature was enabled following the steps listed in Enable ACUL advanced rendering mode without being fully configured.

Example configuration that causes this issue:

{

 "tenant": "<TENANT-NAME>",

 "prompt": "login-id",

 "screen": "login-id",

 "rendering_mode": "advanced",

 "context_configuration": [

  "screen.texts"

 ],

 "default_head_tags_disabled": false,

 "head_tags": [

  {

   "tag": "script",

   "attributes": {

    "src": "<URL_TO_YOUR_ASSET>",

    "async": true,

    "defer": true,

    "integrity": [

     "ASSET_SHA"

    ]

   }

  },

  {

   "tag": "link",

   "attributes": {

    "rel": "stylesheet",

    "href": "<URL_TO_YOUR_ASSET>"

   }

  }

 ]

}

Solution

Either disable the ACUL advanced rendering mode feature or replace the all-caps placeholders (shown in the example above) with appropriate values.

Disable ACUL

Via the Management APIv2:

PATCH to /api2/v2/prompts/{prompt}/screen/{screen}/rendering
{
  "rendering_mode": "standard"
}

Via the Auth0 CLI:
1. Open the Auth0 CLI
2. Select Advanced
3. Select the corresponding prompt and screen
4. Set the rendering_mode to standard
5. Deploy the changes