Hello together,
Problem solved. No direct update from 2.3.3 to 2.3.5 possible. I made a rollback to 2.3.3, then updates to 2.3.4 and then via interim 2.3.5 finally to 2.3.6.1 and it worked. Seems to be a error in the file update list and the link to the source files in 2.3.5 package.
Bye Christian