Error after deleting process

I created a process as a superclass and defined some attributes and a domain. I wanted to delete the process, so I had to delete the domain. Now after I delete the process, I get this error:
com.google.common.util.concurrent.UncheckedExecutionException: java.lang.NullPointerException: classe not found for name = UseCaseProcess, caused by: java.lang.NullPointerException: classe not found for name = UseCaseProcess
When this happens, there are no domains to be found, even though i have several that are not related to this process.
The error disappears and the domains reappear, when i create the process with the exact same name again.
How can i fix this?

i get a similar error when deleting a Class

Error

com.google.common.util.concurrent.UncheckedExecutionException: com.google.common.util.concurrent.UncheckedExecutionException: java.lang.NullPointerException: classe not found for name = Reports, caused by: com.google.common.util.concurrent.UncheckedExecutionException: java.lang.NullPointerException: classe not found for name = Reports, caused by: java.lang.NullPointerException: classe not found for name = Reports