I always get a bunch of warnings in the GUI: 13:24:54: Folder “XXXX” isn’t making progress - check logs for possible root cause. Pausing puller for 1m0s.
Firstly, it is annoying to see this in the GUI 
Secondly the “root cause”: is always
~syncthing~.Track 37 Part 1.mp3.tmp: Das System kann den angegebenen Pfad nicht finden.
in english: system can’t find the path specified. I can access the path but I can’t see the file.
Are you running two sync solutions in parallel or something?
No I tried to put *.tmp on the ignore list but the error appears again
Can you provide more log context around the error? Also, OS/platform, etc.
You got a private message
So I think your problem here is that the total file path exceeds the Windows limits of 250 something characters.
You can edit config.xml manually, and add \\?\ before the folder path, example \\?\c:\path\to\my\folder
Also, this is fixed in 0.11, so you might want to try out the release candidate
thanks! seems to work now with the “?”