The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)

Question

Recently we have been strugling against a new error in a already working (very well) environment.

I have no ideia hyw stopped working, the only event we had it as a 1-hours disconnection of the network to a Switch Swap, but no reboot

My Veeam Backup Servers are no longing connecting properly to my Win2022Hyper V Servers (with or without cluster involved)

Thre is no firewall active, no AV installed and both machines are in the same network/collision and broadcast domains)

At first, the DCOM RPC_C_AUTHN_LEVEL_PKT_INTEGRITY is not an issue, as all OSs are fully upcdates, the client App is running on its latest version 12.0.0.1420 P20230718 and as KB, fully compatible with the DCOM high security requisites

the regkey ActivationFailureLoggingLevel is 1 and no relevant events are appearing, but maybe here, there is a clue:

DCOM was unable to communicate with the computer HYPER_VSTD using any of the configured protocols; requested by PID 3ba4 (C:\Program Files\Veeam\Backup and Replication\Backup\Veeam.Backup.Satellite.exe), while activating CLSID {8BC3F05E-D86B-11D0-A075-00C04FB68820}.

We try to use a these-commands:

Get-WmiObject Win32_ComputerSystem –ComputerName NODE1 (win2022 fully Updated)

and

Get-WmiObject Win32_ComputerSystem –ComputerName NODE2 (win2022 fully Updated)

And the result is intermiten, sometimes works and sometimes it doesn´t

In a matter of less than 60 seconds we have:

PS C:\Users\fborup-adm> Get-WmiObject Win32_ComputerSystem -ComputerName brrj1-srv0140

Get-WmiObject : The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)

At line:1 char:1

• Get-WmiObject Win32_ComputerSystem –ComputerName brrj1-srv0140

• 
      + CategoryInfo          : InvalidOperation: (:) [Get-WmiObject], COMException 
  
      + FullyQualifiedErrorId : GetWMICOMException,Microsoft.PowerShell.Commands.GetWmiObjectCommand 
  
  

PS C:\Users\fborup-adm> Get-WmiObject Win32_ComputerSystem -ComputerName brrj1-srv0140

Domain : qgog.ad

Manufacturer : Dell Inc.

Model : PowerEdge R650

Name : ClusterNode1

PrimaryOwnerName : Windows User

TotalPhysicalMemory : 549180764160

Answer 1

Hello KayZerSoze

There can be a few reasons for this problem:

1. Incorrect DNS settings.
2. Incorrect Time and Time zone settings.
3. The "TCP/IP NetBIOS Helper" service isn't running.
4. The "Remote Registry" service isn't running.

You can try the following methods:

1. Verify correct DNS settings.
2. Verify correct Time and Time Zone settings.
3. Verify that "TCP/IP NetBIOS Helper" is running and set to auto start after restart.
4. Verify that "Remote Registry" is running and set to auto start after restart. Reboot the computer after changing the required settings.

Best Regards,

Hania Lian

Answer 2

Thank you for your answer!

Unfortunately, those procedures were already checked before. Those and many others

At the end, the error was "intermitent", sometimes working and sometimes not

WMI repo was consistent and perfectly in working order, answereing WMI calls, locally, with no problem

So, as the error was 0x800706BA and not a classic "access denied error", my attention turned to WMI issues

And I considered to patch the system with a 2021 patch related to high security DCOM communication, but the DLLs of the Win2019 were far ahead, from 2023. The source Win2019 has been fully update by ManagedEnginePatchManager, so this was not the case

Then I noticed that only when the WMI tests are being done by Win2019 but not from the cluster members itselves, the problem was clearly tied to my WIn2019 and WMI security issue, as firewall was fully disabled, etc.

The solution I did a "in-place" upgrade from Win2019 fully patched using the DVD Win2022 August2023 from VLSM and... it works!

Flawlessly! Now the system is up and running, Backup is running with no issues at all and the "in-place" upgrade kept all configurations, etc... and....it´s ok now

Weird problems.. weird solutions

I didn´t like the solution, i might be happy if I discovered exactly what was going on, but I have no more information for now

Answer 3

Hi fborup,
I'm trying to find a way to create a .bat file that kills processes on remotely connected machines.
I have 31 computers connected through a 100G mellanox switch, networked in a 10.10.10.X range with a 255.255.255.0 subnet.
Using CMD, I run a command: Taskkill /s "hostname" /IM "Process" but a get a return "RCP Server is not available".

Could you advice on how you set up before?

Thanks1