Could be so many things... if you google "0x8004230f vss" you will see what I mean.  Checking event log for related or more messages might isolate resolution process.

Is this Windows 2008 R2 systems?  Do you have a version of NetWorker client on them that supports 2008 R2?

I have the same problem since the costumer did install some microsoft patches (after Patchday)

I found this site in the web. the costumer will try this workaround

Yes, that's the solution!!!! Thank you a lot!!

And the problem was really after install some microsoft patches!

But it is unacceptable that that this action is a solution forever.
It doesnt save DEASTER_RECOVERY anymore. What should I do, if some day my backup server is down and i have to
recover this backup ? Will it be work?

My understanding is that you setup a different "client" (same client name) with the DISASTER_RECOVERY selection and don't include the VSS stuff in the save sets. That way you get the regular backups and the DISASTER_RECOVERY. Use a different schedule for the DISASTER_RECOVERY like once a month or every 2 weeks.

I don't think that is solution to this problem. The thing is, if you unchecked DISASTER_RECOVERY save set, you will not be able to BMR (Bare Metal Recovery) that machine. Tried it, it didn't work.

Has anyone tried a re-register of the VSS?

Hi all, I have the same issue. I can't backup my VADP Proxy anymore. The issue started to come up after some MS patches and the change from diskpart: automount disable. Nothing else has been changed on that system.

Tried several approches I have found, none of the worked. Anyone might have a good idea?

I have found the problems and was able to fix them. Within the application log of Windows it has shown two VSS errors:

Event 8193

Volume Shadow Copy Service error: Unexpected error calling routine RegOpenKeyExW(-2147483646,SYSTEM\CurrentControlSet\Services\VSS\Diag,...).  hr = 0x80070005, Access is denied.

To fix that one, I had to give the NETWORK SERVICE user full access to that registry key. Within the details pane of the event log, you'll find the affected user. It looks something like this:

0090: 2D 20 55 73 65 72 3A 20 - User:
0098: 4E 61 6D 65 3A 20 4E 54 Name: NT
00a0: 20 41 55 54 48 4F 52 49 AUTHORI
00a8: 54 59 5C 4E 45 54 57 4F TY\NETWO
00b0: 52 4B 20 53 45 52 56 49 RK SERVI

Event 12293

Volume Shadow Copy Service error: Error calling a routine on a Shadow Copy Provider {b5946137-7b9f-4925-af80-51abd60b20d5}. Routine details EndPrepareSnapshots({49a815d6-9ff2-473a-9659-72f81332a966}) [hr = 0x80070015, The device is not ready.

I found a lot of theories on what could be wrong. The simplest one helped me: assign a drive letter to the System Reserved partition in the disk manager for Windows.