I've been having issues with VBO for a few weeks. A lot of the mailboxes are failing during the backup, with the following error :
2017-06-12 11:14:31 PM :: Processing mailbox xxxxxxxxxx failed with error: JetError -1085, JET_errTempPathInUse, Temp path already used by another database instance
When I reboot the server, it often works fine for a day, but the next day it fails again. Note that not all the mailboxes fail, and that, from one day to the next, it's not necessarily the same mailboxes that fail.
I opened a case with the support, but all they told me was that I should reboot the Exchange server, which is impossible since it's Office365. They then asked me to check with Microsoft. However, I'm not sure it's an issue on their end. Mostly because I doubt our Office 365 instance is that different than others. Also, it was an error that was supposed to be fixed with Update 1 (which I am running).
So I'm putting this out there, to see if anyone had the same issue.