PHP last error: An error happened at: disk.php(812)

Taking over some admin work on a site that uses your backup solution. The last successful backup was in mid-March. The backups are 350mb.

Online backup: 3.0.4.
WP 3.6.1.

I don’t want to update WP until I get a good backup (again, I have no idea if updating will break anything the previous admin may have done).

Here is the line from the event log:

The activity failed: Attempt to write to file /home4/aardaweb/public_html/wp-content/plugins/wponlinebackup/tmp/backup.zip.enc.ceadebc7f97b1fca05ee996f2dac62e19fe9e51b.rc.php only partially succeeded.
Only 0 of 0 bytes were written. (166274688 bytes already written.) PHP last error: An error happened at: disk.php(812)
unlink(/home4/aardaweb/public_html/wp-content/plugins/wponlinebackup/tmp/cdrbuffer.f5db944ec9c8f6675bc0e8e6fea76a3cf7a49b01.1.php): No such file or directory

Thoughts? Suggestions?

https://wordpress.org/plugins/wponlinebackup/