The authentication service is unknown

[Zew]

Case #01982435

Power on a Proxy machine, go to scan in Veeam (just a simple laptop worked every time I did this) but this time randomly:

10/5/2021 7:17:42 PM Error [ProxyHostname] Microsoft Windows server discovery failed Error: The authentication service is unknown.

RPC function call failed. Function name: [GetSvcVersion]. Target machine: [ProxyFQDN:6160].

10/5/2021 7:17:42 PM Error Failed to rescan repository Offline Repo Error: The authentication service is unknown.

RPC function call failed. Function name: [GetSvcVersion]. Target machine: [ProxyFQDN:6160].

10/5/2021 7:17:42 PM Error Host discovery failed

What gives? Things I already tried:

I can ping the host via FQDN, yes, issue is not DNS related.
I can access the admin$ share via explorer from Veeam, at least with my admin account, I didn't verify via the account specified to manage the server.
I disabled the firewall on the Proxy, no dice.
Rebooted the Proxy, even though it was from a power off state, no dice.
Checked all Veeam services on the Proxy, all show to be running.

If I try to add the host a new, or edit the existing object properties and click next I get: "Can't create persistent connection to admin share", I've blogged about this and mentioned this serval times in Veeam threads as seen hereveeam-backup-replication-f2/failed-to-c ... 36932.html and herevmware-vsphere-f24/v-11-lacks-backwards ... 94-30.html

Even though it is ridiculous I even added the registry key to disable UAC and the same errors are reported when I either rescan (first error in this post) or edit or re-add (second error in this post).

What gives? What else can I possibly try, this feels like some odd software issue.

Also note, I can't say for sure when I updated my Veeam server to the latest, I can't remember if it was before the last time I ran the job or not, is there anyway to know what version the Veeam server was on the last time the managed server was scanned successfully?

[HannesK]

Hello,
sounds like the pre-requisites are okay. (well, the admin$ share needs to be accessible by the user that is configured in the managed server credentials section if it is different than "my" admin account)

can you maybe check the case number? It should start with 05...

Thanks,
Hannes

[Zew]

Case #05061726

It was your comment to check the account used, which of course it couldn't. I then checked the proxy's local admin group and the account was not in there. Honestly I can't remember if that was how I initially set it up. My documentation has been a bit terrible lately.

However I added the account into the local admin group and a rescan worked fine. I was working on some GPO's and then it hit me that the GPO's might have changed the local admin group for that proxy server.