Updated to 2.5.0 still errors

Updated all-in-on-calendar to 2.5.0 and still get error 500 when trying to go in to settings . get this message:
Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, support@one.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

I updated the wp-config.php but this don’t help anything.
Its time to get a working version without all this errors or i’m going to say goodbye to this plugin.
The least that should be working is the settings .

I tried all sorts of things to get it back working : deleting , installing a older version , installing a new version . It all started with the new ticketing item.

I give this plugin a week and if it is not working like it did before I’m going to search for something else .

My clients are getting furious at me . SO get it all working please .
Drop if it is neccesary the ticketing item and start from a working version and search out with a dummy website all plugins if the ticketing is not breaking the website or your plugin.

that’s my opinion .

regards
RT