I’ve been using Veeam Backup for Office 365 since somewhere around November 2016. Being part of the Vanguard program, I was afforded an early glimpse at it. I quickly found that I was getting some great use from having it though. Although generally smooth, I do occasionally run into issues.
Most recently, I ran into an interesting error message while exporting a mailbox: Unable to read beyond the end of the stream. Definitely not an intuitive message, however it does sound like some sort of read issue. Being the type of person that I am, I immediately took a look to see if I could fix things myself before evoking support.
NARROWING DOWN THE PROBLEM
The first thing I did was check my log files for Veeam Backup for Office 365. By default, you can find these in c:\programData\Veeam\Backup365\logs. I looked through here for quite a while but couldn’t find anything. I tried following entries by using TextPad and reloading the file every time there was a write, but no luck. It then occurred to me why I wasn’t seeing anything. When restoring data from the backup, Veeam Explorer of Microsoft Exchange is used.
Once that light bulb went off, I looked at the Explorer for Exchange log files. These files are located in C:\ProgramData\Veeam\Backup\ExchangeExplorer\Logs by default. This time I was able to find the error message in the log file. At this point, I opened up a support case and sent along the log files, but I kept digging some more.
I noted that there was a reference to Deleted Items right before the error. This led me to believe that the error was related to an item in the Deleted Items folder. I did some testing by exporting the Delete Items folder, which threw the error after a few minutes. I then tried a few other random folders, and all was fine. This pretty much confirmed my suspicion that the problem was with an item in that folder.
FIXING THE ISSUE
I was happy that I opened the case because as it turns out, the fix requires updating some of the DLLs required for the program. I don’t have the technical details, but it would appear that either the items are fixed or ignored in the new version. Without knowing which item was causing the trouble, I can’t confirm which method is used.
Also part of the fix is that you need to run a full backup to a new repository. In my case, I setup a new share and pointed to that location for the repository. The old repository is still accessible with Veeam Explorer for Microsoft Exchange, so I can get at the data if need be.
I thought I would share this information as it was not immediately apparent to me on how to solve the problem. If you need to perform a restore, but keep receiving this error, check your log files. You might be able to figure out where the problem is, and avoid the specific folder.