Windows Virtual Desktop - Troubleshoot a WVD session host that is unavailable


In a Windows Virtual Desktop (WVD) installation with multiple session hosts, one (or more) of the session hosts can be shown as “unavailable” in the Azure portal. We will need to troubleshoot the problem to detect the reason for this.


Whenever you find the SH showing as “Unavailable” state, please go through this MS Article as it describes the same issue and you can follow the step by step process.

You can also follow the below steps to check the session host from your end and troubleshoot based on the event IDs:

  • Event ID 3277:
    • It talks about the registration and to fix this issue, you have to re-register the SH in the host pool to fix this issue.
    • You can follow this article to re-register the SH to the Hostpool.
  • Event ID 3702:
    • Source WVD-Agent.
    • This event ID gives you a specific set of URLs you need to whitelist for your virtual machines.
    • These URLs are specific to the region in which the virtual machines are deployed and procedure needs to be repeated for virtual machines deployed in different regions.
    • For example please take a look at the below screenshot:


  • Event ID 3703:
    • This talks about the Session Host is not able to reach the RdBroker.
    • For example please take a look at the below screenshot:


    • This means your SH is not able to reach the RdGateway and in this situation, you will get the Unavailable state.
    • You can also verify the communication between the RdGateway and SH by doing the below steps:
    • Please login to SH and open the cmd
    • Please run this NSlookup, it should not be resolved however, if it gets resolved, please do the below:
    • Open registry and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\RDInfraAgent
    • Note values of BrokerURI and BrokerURLGlobal


    • Now, open browser and go to:
      • https://”BrokerURI”/api/health
      • https://”BrokerURIGlobal”/api/health


    • If network is blocking the pages won’t load, for example:


    • You need to confirm if the below URLs are reachable from the VDI or not. If not please check with your Network team.
* 443 Service traffic WindowsVirtualDesktop 443 Agent and SXS stack updates AzureCloud
* 443 Agent traffic AzureCloud
* 443 Agent traffic AzureCloud 443 Agent traffic AzureCloud 443 Azure Marketplace AzureCloud 1688 Windows Activation Internet 443 Azure portal support AzureCloud 80 Azure Instance Metadata service endpoint N/A 80 Session host health monitoring N/A

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This post was first published on Stathis’ log book by Stathis Athanasiadis aka StatAth