The reason for the error is because it's trying to delete the temp files in the /tmp dir of the server.
Which you do not have access to delete those files.
I found my solution to be a bit more correct, as the application was designed to have a temp file system. Yes you can comment out the line db_cachedir:
But you can also change it to another path.
Example: db_cachedir: /home/user/tmp_cal
Then CHMOD permissions to 0777
This will let the application do what is was designed to do.
Also remember for security reasons do not make db_cachedir: in or after www or public_html
Hope this helps others..
-Anthony
