ECAS authentication ends up with internal server error 500

[zubanst]

Describe the bug
Owncloud 10.6.0.5, on top of Ubuntu server 18.04 with Apache 2.4.29 and php 7.2.24, CAS app latest version installed and configured with the EU ECAS server. User [email protected] created on Owncloud server and can authenticate on the ECAS server. After the authentication, on the Owncloud server, authnetication is rejected with Internal Server error 500

To Reproduce
Steps to reproduce the behaviour:

1. On the Owncloud 10.6.0.5 server the CAS app latest version is installed and configured with the EU ECAS server:

CAS Server version: 3.0
CAS Server Hostname: ecas.ec.europa.eu
CAS Server Port: 443
CAS Server Path: /cas
Service URL:

2. On the Owncloud 10.6.0.5 server, user [email protected] is created. User can authenticate on the ECAS server.
3. From the Owncloud 10.6.0.5 Web frontend, click on CAS login button
4. User is redirected to the ECAS login page. User authenticates with [email protected] and password. Authentication is successful, but when redirected back to Owncloud server, the following error is displayed:

_Internal Server Error
The server encountered an internal error and was unable to complete your request.

Please contact the server administrator if this error reappears multiple times and include the technical details below in your report.

More details can be found in the server log.

Technical details
Remote Address: 192...*
Request ID: dZpbhjQg9fSTtZT42PsE_

Expected behavior
After te successful authentication with ECAS, it was expected to be redirected to the [email protected] Owncloud welcome page

Screenshots

Software (please complete the following information):

• Server-OS: Ubuntu 18.04
• HTTP-Server Version: Apache 2.4.29
• PHP-Version: PHP 7.2.24
• phpCAS-Library-Version: 1.3.3.4 (distribution library)
• ownCloud/Nextcloud Version ownCloud 10.6.0.5
• user_cas-Version: ?
  owncloud.log

Additional context
Add any other context about the problem here.

[felixrupp]

Hello @zubanst,
can you please provide an excerpt from your php log of your server? Server Error 500 are thrown on PHP level, not on application level.

Did you check, if you have permission to register your owncloud instance for the ECAS authentication? As far as I know, your application must be listed in the ECAS instance.