[SOLVED] Event Error 4879 when doing a Snapshot backup on my Windows VM

[Darkbotic]

Every time I do a Snapshot backup on my Windows VM on Proxmox, this Error shows up on the Warning list.

Error ID: 4879

MSDTC encountered an error (HR=0x80000171) while attempting to establish a secure connection with system WINDOWS-VM.

I've been able to reproduce the same issue on multiple Proxmox hosts (4) running the latest VirtIO Drivers on the latest version of Proxmox.
This specific error only happens when I do a Snapshot backup. It doesn't happen when I do a Stop backup.

How can I fix this?

Thanks in advance!

 

[Darkbotic]

I found the solution for this myself. You have to do the following in the Windows VM:

1. Click the Start menu and type Component Services
2. Double click Computers > My Computer > Distributed Transaction Coordinator
3. Right click Local DTC > Properties
4. In the Security Tab, enable "Network DTC Access" then select "Incoming Caller Authentication Required" and click OK

It should look like this:



There's another error (8194) that is related to Proxmox snapshots.
The solution for that one can be found here.
Basically, you have to do this in the Windows VM:

1. Click the Start menu and type Component Services
2. Double click Computers
3. Right click on My Computer and click Properties
4. In the COM Security Tab, in the "Access Permission" section, click Edit Default... then add the NETWORK SERVICE user and enable "Allow" for the "Local Access" permission.
5. Click OK twice and restart the VM.

It should look like this:



Reboot the VM for the changes to take effect.
Hope this helps someone!

 

[akxx]

just to add automated way for DTC change:

Set-DtcNetworkSetting -DtcName "Local" -InboundTransactionsEnabled $true -AuthenticationLevel Incoming -Confirm:$false
Restart-Service MSDTC

 

[akxx]

to automate DCOM default access permission:

DComPermEx.exe -da set "NT AUTHORITY\NETWORK SERVICE" permit level:l,r

with DComPermEx source here