Error "access_denied: Cannot read property 'endsWith' of undefined" when trying to Debug the Keycloak Application

Last Updated: Feb 20, 2026

Overview

When trying to Debug the Keycloak Application SAML 2.0 Addon, the following error is received:

access_denied: Cannot read property 'endsWith' of undefined

Steps to reproduce the error:
1. Click on Keycloak Auth0 Application.
2. Click on Addons.
3. Click on SAML 2.0 (not disable, click on the text).
4. Scroll down and click Debug.
5. New page opens with error.

This article details why this error appears and how to get past it.

Applies To

Keycloak Application

Cause

The error is coming from the Rule “Adding Roles to Access Token and ID Token”.

user.issuer.endsWith(endsWith)

The issuer is undefined.

Solution

There is a misconfiguration in the rule. Disable the rule or add a null check to the line user.issuer.endsWith(endsWith).