Azure Backup Server – Error 104 Fixed

Problem

When performing a nightly backup of an on-premise VMware guest to Azure using the Microsoft Azure Backup Server (MABS). The backup would fail every time with the error;

Online recovery point creation jobs for VMware MyServer on MyVCetern have failed X times. (ID 3188)
An unexpected error occurred while the job was running. (ID 104)

Troubleshooting

Reinstalling and reconfiguring the Microsoft Azure Backup Server didn’t help. I verified the VMware VCenter credentials were all good.

In the CBEngineCurr.errlog log file on the MABS server, in my case located under C:\Program Files\Microsoft Azure Backup Server\DPM\DPM\Microsoft Azure Recovery Services Agent\Temp\. I spotted an odd error

0x80070037 Failed to get the SCSI address for the disk

The above message was followed by the path to a VHD file on the MABS server under C:\Program Files\Microsoft Azure Backup Server\DPM\DPM\Cache\Scratch

I used Disk Manager to confirm there were no VHD’s mounted.

Solution

After exploring the DPM\Cache\Scratch path I had found in the CBEngineCurr.errlog I discovered a large number in “DiskCache_” files in the scratch folder, all 0 KB in size.

As this is a cache directory I decided to delete them in case one was clogging up the process.

After that I ran a backup and it succeeded fine.