Can not login in the control panel: Internal Server Error 500
The error was caused by the configuration in general.php, which works fine local and on three other websites.

For production environment, I added 

'userSessionDuration' =&gt; 'P101Y',
'rememberedUserSessionDuration' =&gt; 'P101Y',
'rememberUsernameDuration' =&gt; 'P101Y',
'invalidLoginWindowDuration' =&gt; 'P101Y',


Now I removed it and can login in the cp - no idea why.