Synthetic full backups succeed but incremental backups fail (0x80070721)

[Norclair]

[related to Case Id #04648926]

Backup for my Exchange 2013 VM started behaving strangely a little while ago: synthetic full backups still succeed (once a week), but incremental backups fail with error 0x80070721 (A security package specific error occurred).

It is running with Domain Admin credentials...

Anyone has an idea as to what could be wrong and where to look next? Thank you!

[HannesK]

Hello,
and welcome to the forums.

I searched the internet on 0x80070721 and it looks like the error is unrelated to Veeam.

Veeam cannot help you without logs (as far as I see, you did not upload logs to the case) https://www.veeam.com/kb1832

Best regards,
Hannes

[Norclair]

I realize error 0x80070721 has to do with security and potentially DCOM, and is most likely caused by a WMI call that's being attempted by Veeam. Since the behavior experienced in Veeam is unstable (full backup vs. incremental backup), I was hoping someone could point me in a direction that could provide a clue as to what the root cause is.

Regarding the logs, I tried the approach suggested in KB1832 but somehow it exports logs back from a long time ago (!).

Anyways, I'll keep looking into this and report back if I find something.