I am sorry but, not all forum user speak german ... I know I don't... so I don't have a clue of what that error is trying to say...
Please remember that you are in the international (english) part of the forum... and, although Code is always in english, logs are in the IDE selected language,...
My guess is there is a released compilation running on the background that didn't terminated correctly and you are trying to compile the app with same name.
I am sorry but, not all forum user speak german ... I know I don't... so I don't have a clue of what that error is trying to say...
Please remember that you are in the international (english) part of the forum... and, although Code is always in english, logs are in the IDE selected language,...
My guess is there is a released compilation running on the background that didn't terminated correctly and you are trying to compile the app with same name.
I would also check what happens after a reboot of your PC. Additionally, the Windows OS might be accessing the file as part of indexing the Files directory. In that case, you could remove the directory C:\Users\franz\Documents\B4X from indexing (but you will lose the ability to search for a file in that directory).