Recently we were troubleshooting an issue in System Center Virtual Machine Manager 2012 R2 where running a compliance scan against Hyper-V hosts was failing with the following error:
Error (2931) VMM is unable to complete the request. The connection to the VMM agent on the virtualization server (server01.domain.local) was lost. Unknown error (0x80338029)
The issue was present on all Hyper-V hosts, most of them running Windows Server 2012 R2. The latest Windows updates was installed on the hosts, and Virtual Machine Manager was running the latest Update Rollup available.
During troubleshooting we uninstalled System Center Endpoint Protection from the Hyper-V hosts, and noticed that compliance scan worked immediately.
After opening a support case with Microsoft, we were advised to decline all superseded updates for System Center Endpoint Protection from the WSUS server.
After doing that, compliance scan worked as expected on hosts with System Center Endpoint Protection installed.
The issue is explained in more detail in this article, where there is also a Windows PowerShell script available for automating the cleanup process. It can be accomplished by using the WSUS clean-up wizard, but this process should be automated and run on a scheduled basis for example once a month to prevent the issue from happening again.
The referenced article states the following:
A hotfix for the Windows Update Agent is currently in development. The update will change how the update metadata is loaded into memory. Pending the results of final testing, this fix should be available late in the 2nd quarter of CY2015. This post will be updated with more information as it becomes available.
From a VMM perspective, the error message is quite misleading when compared to what the underlying root cause is. A suggestion to improve the error message has been posted to Microsoft’s VMM User Voice.