Did you set "/mnt/user/appdata/nextcloud/temp"? If yes, are there any files in this folder when you upload files?   Alternatively upload your file and execute this command through the Webterminal: find /var/lib/docker -type f -printf "%T@ %p\n" | sort -n | cut -d' ' -f 2- | tail -n 50   It shows you the 50 most recent files in the docker.img.