Hi @Danyang007 -

Welcome to the Community. Have you looked at the User Guide for assistance? Make sure you've met the prerequisites and use an Administrator account to add your Host, in the format  DOMAIN\USER or MACHINE\USER. 

Can you provide more information?

What version of Hyper-V?

Is the host standalone or in a cluster?

What version of Veeam?

Have you checked the Helpcenter and made sure all pre-reqs are met? https://www.veeam.com/documentation-guides-datasheets.html?productId=8&version=product%3A8%2F221

Hi @MarkBoothman 

The Hyper v version is 10.0.17763.1

Its standalone

Veeam version 12.1

Veeam Server is Windows Server 2019

Problematic server is also Windows Server 2019

All prerequisites are met.

The server is not on a domain.

credentials format is server01\Administrator (inbuilt Administrator)

I already added one server succesfully, but the other two servers is refusing to add

can you get to the other 2 servers via UNC and successfully browse resources?

Hi @MarkBoothman,

Yes I can.

Using both IP\c$ and IP\Admin$ format.

how about %hostname%\admin$ ?

I could reach the share using %hostname%\admin$ for one of the server

The other server failed when I used %hostname%\admin$

Sorry tried again and both servers are reachable using %hostname%\admin$

Hi @Danyang007 -

Some common issues adding HV to Veeam are:

• Credentials (sometimes using .\user works, as noted in 1 of the posts I’ll share below)
• HV server has firewall enabled; temporarily disable, try to add, then re-enable
• UAC is enabled; disable then attempt, then if required..re-enable
• HV host needs to be fully patched, rebooted, then re-attempt to add
• If role was just added and not yet rebooted, reboot, then re-attempt to add

Some of these fixes are found in a few of the following previous Hub posts:

Try these and see if you can then connect.

Also, even though you were able to connect with your other Hosts, if your HV host isn’t on the domain, and are trying to use a local admin account, you may need to add a registry fix to enable a local admin to be used to connect to by Veeam or any other service. See my comment which helped this user for another issue in the post below:

Lastly, make sure DNS is setup correctly since this HV Host is not on the domain

Hi @coolsport00 ,

Thank you for your response.

Will try your suggested steps and hopefully it works

Sure...keep us posted!

Hello Guys,

I finally resolved the issue thanks to @csmithconvergence writeup.

The resolution is to install Microsoft KB 5034127 on the Veeam server. i restarted after the installation and everything went smoothly.

https://catalog.s.download.windowsupdate.com/c/msdownload/update/software/secu/2024/01/windows10.0-kb5034127-x64_7ac59afbc502ef9dc77f7584b31110ea0b23a566.msu

Great to hear!..and thanks for posting what worked for you.

So glad this was helpful for you - thanks for the note and the acknowledgement!

This info has been super helpful! I have a similar issue, however, I am running Server 2022 and KB5005102 is not an available update for that OS. I’ve tried changing the DCOM hardening settings, modifying UAC, ensuring local Administrator accounts are used. Nothing has worked. 

@Jmaeser82 - would be best if you contact Support for them to try and address your connectivity issue.

Hello @Jmaeser82 

Has this issue been fixed?

KB5005102 is for Windows Server 2016

KB 5034127 is for Windows Server 2019, might even work for 2022

So there may be an updated KB verion for Windows Server 2022 

I know you have tried those steps you listed. Have you tried windows update on that server?

Maybe a Windows update can fix the DCOM hardening setttings and fix the issue, just maybe.

Thanks for checking in @Danyang007! I was able to resolve and I’m embarrassed to admit, it was the username format. On the Veeam server, I simply added the username/password instead of <hyper-v hostname>\<local admin username> and I was good. I was able to reverse the DCOM setting I changed previously and everything essentially worked out of the box on 2022. 

@Jmaeser82 

Thank you for coming back to drop your resolution.

Glad it was resolved. 

Yes, this is because the patch will continue to be included in the cumulative updates!

I’m still running in a similar issue.  Backup device is Windows 10 Standalone running the latest version of Veeam 12.  HyperV host is 2019 standalone.  This worked fine for a long time until MS patched the host and now the veeam server is unable to connect.  I have run every fix from every article I have found and still nothing.  I can rip Veeam 12 off and run Veeam 11 and it works fine.  I am using the Built IN Admin account on the HV host as well as it worked with a different local account originally.  No local firewall in play.  I can connect to \\servername\admin$ just fine.   If I roll back the patch from January it works but each month the cumulative update breaks it again and I don’t really want to keep the HV host unpatched.  I don’t want to add it to the domain either.  The above KB article does not apply when I try to run it on the Veeam server (windows 10).  I have tried servername\username and just username, no dice.  the above mentioned KB’s don’t apply when I try to apply them.  I did find more DCOM changes and i will reboot here to see if they address the issue. 

Furthermore, I uninstalled V12 and install Veeam 11 an still get the same error.  Backup device is also added to the domain however HyperV host is not.

Hi, did you follow the marked answer correctly? Uninstalling and reinstalling is not the fix to this issue. Also, see this link below, you will find some suggestions to resolve this issue.

I have tried the above mentioned fixes.  Nothing works.