Thanks for the response. There are some warnings in the .err file but they’re all related to the model and not the “solver” itself. I cannot find anything that would lead to a total crash and not just an error prompt during the solving provess.

I know that I can override or delete the lock file but when I try to run it again APDL crashes again...

The same model does run with the USERMAT linked via the .exe file so I know that it does run through. I just have no clue why the linking with the dll library does not work. When I compile files beforehand with ansusershared.bat it does create dll and other files but the linking to APDL with the system variable ANS_USER_PATH somehow does not work (even though it says in the command prompt: This version is linked by licensee).