Just wanted to drop a not about this issue … I found another thread that never added a solution, but the thread was closed.
I found that a file (did not spend the time to find the specific file) was corrupt in the bin dir. I renamed my programdata dir to *_bak and reinstalled. After a new install Sonarr was running again… I renamed current dir to *_new and put the *_bak dir back as the default dir and then copied everything in the bin dir from the *_new to the original bin dir.