I am getting the same error with 3.5.3. We upgraded in November and in the last few days this error has come up. We have several courses that are no longer backing up properly, even though nothing has been done to them for months.
One of the things our IT guys have found is space on the server goes from 2-4G to 0 and those course backups fail. In the interim we are allocating more space to the server. We have deleted the contents of the temp and trash directories. The temp one several times.
Unfortunately, upgrading to 3.6 is not an option as we are already pushing the limits of the server OS. We do plan on getting a new server prior to upgrading to 3.6 or 3.7.
I would like to know a few things
- What causes this error? Especially, if we have not performed any updates/upgrades in the past several months.
- What is the minimum required disc space? It seems the available space issue is what is causing the backups to fail and give this "sessions" error. I realize back up size is a function of how much content we have. However, I have added less than 500M of stuff in the last few months.
- Is there any admin setting I can adjust to try to minimize the occurrence of this error? I only have access to the admin functions in Moodle nothing outside at the server level.
That is enough for now. I am sure something else will come up.
Thanks in advance for any assistance.