apache php, kerberos problem

I have a problem with kerberos authentication on apache php
Setup = RHEL 7
apache 2.4 from rhscl
php7 from rhscl configured with php-fpm

Kerberos is working perfectly on http://site.domain/
but not on http://site.domain/index.php

The same problem occurs for all sub directories when accessing a .php file.

There is a rewrite for php to fcgi in the vhost setup.