rsync: mkstemp failed: Protocol error (71)

Question

I ran into this issue with an rsync script after I changed the destination from a local directory to a CIFS mount. All of the files in the source directory will throw this mkstemp protocol error and the process will still take a regular amount of time to complete despite no files showing up in the destination.

root@VirtualBox:/# rsync -aPh --progress [email protected]:home/backup /mnt/1TBHDD/backup --delete
receiving incremental file list
backup/
rsync: mkstemp "/mnt/1TBHDD/backup/.2022-05-22T13:09:38_db_backup.sql.gz.JVyRsP" failed: Protocol error (71)
         52.49M   0%   50.06MB/s    0:02:39 

Answer 1

The issue was not with rsync as I originally was thinking, but rsync passing through an error message. Running:

touch /mnt/1TBHDD/backup/.2022-05-22T13:09:38_db_backup.sql.gz.JVyRsP

returned:

touch: cannot touch '/mnt/1TBHDD/myfile/.2022-05-22T13:09:38_db_backup.sql.gz.JVyRsP': Protocol error

The error is because colons are not allowed in windows/CIFS filenames. Changing my naming convention away from those characters resolved the issue.