Tar backup issue

Having a minor issue with permissions.

I have been running backups via the tar procedure which has been working fine.

I have OpenVPN installed and CUPS for AirPrint - they both work fine.

Currently when I run a tar backup I get:

tar: .kodi/user data/addon-data/script.openvpn/
tar: openvpn.log: cannot open: Permission denied
tar: .kodi/temp/commoncache.socket: socket ignored
tar: Exiting with failure status due previous errors

openvpn.log has rw Owner permissions and a Numeric value of 600.
commoncache seems to require root access.

I can fix the OpenVPN issue by deleting the log file - not ideal.
I have no idea how to fix the common cache issue.

1/ What do I need to do to fix this error message?
2/ Can the error message ust be ignored or has the .tar backup indeed not completed fully? or
3/ Has the .tar backup completed just not including the above files?

Thank you.

Oh, and if I use the OSMC settings backup method will the above errors affect the backups created?