[TYPO3-mvc] Extbase Exception Handling for TYPO3 CMS 7.6.14

[Frederic Born]

Hi to all of you,
I'm new in this forum, so please forgive me if I forget something to post.

I have a problem with the Exception Handling for my Extbase Extension. I tried to follow the instructions on:
- blog.mindscreen.de/2013/404-handling-statt-exception-in-extbase-catching-1297759968/ 
- nerdcenter.de/extbase-fehlerbehandlung/ 
but it seems like my try-catch-Block doesn't work.  I tried it with an abstract ActionController which overwrites the "processRequest"-function as well as to overwrite the "processRequest"-function direkt in my ActionControllers.
It still produces this error:
"#1313855173: The controller "someRandomText" is not allowed by this plugin. Please check for TYPO3\CMS\Extbase\Utility\ExtensionUtility::configurePlugin() in your ext_localconf.php."

For me it looks like that the exceptions which are thrown in i.e. "RequestBuilder.php" can't be catched with my overwritten "processRequest"-function. 
My Code looks the same as in the Tutorials I've followed. 

Has anyone an advice for me? (It seems to me that I'm not the onlyone struggling with that problem)

Thank you very much