Ok, that already helped me a bit. The talk about a finished job was a bit misleading, but that was my error as I didn't differentiate model/print job in remove files. I also found that when uploading fails it tries to delete a job from print queue with same id, so now it is a bit hard to figure out what is the initial cause.
Could you have a look at your server.log file (in storage directory/logs). My guess is that uploading the file somehow fails. In the catch for this case we try to delete the created files to clean up everything. You should see in the log a message
"Creating new model caused error ..."
with hopefully some more informations on what caused the upload to fail. Eventually a restart of the server helps to get it working again, but that depends on the error causing the initial error. If it is the gcode causing a fail, please mail it or put it on pastebin so I can try uploading it and finding where the real problem is.
