Microsoft has resolved a known issue that triggers Cluster service and VM restart issues after installing July's Windows Server 2019 security updates.

The company acknowledged the bug in a private advisory seen by BleepingComputer three weeks ago and asked businesses to reach out for support to mitigate the cluster issues.

As Redmond explained at the time, the Cluster service (a system component essential to cluster operation) may fail to function correctly after installing the KB5062557 update released on July 8th, while some nodes might also fail when attempting to rejoin their cluster and triggering errors on systems with the BitLocker Windows security feature enabled on Cluster Shared Volumes (CSV) drives.

"After installing the July Windows security update [..], the Cluster Service on Windows Server 2019 might repeatedly stop and restart, causing nodes to fail to rejoin the cluster or enter quarantine states, virtual machines to experience multiple restarts, and frequent Event ID 7031 errors within event logs," Microsoft said.

"If you need help to manage this issue on your organization and apply a mitigation, please contact Microsoft's Support for business."

Microsoft has now fixed this known issue in the August 2025 KB5063877 cumulative update for Windows Server 2019, which also includes other significant improvements and bug fixes.

To install it on affected systems, admins must first deploy the KB5005112 servicing stack update and then install KB5063877 via Windows Update, the Microsoft Update Catalog, or Windows Server Update Services (WSUS).

On Wednesday, Microsoft resolved a widespread WSUS issue that prevented organizations from deploying the August 2025 KB5063878 cumulative update on Windows 11 24H2 devices.

Last month, it also addressed another WSUS bug that blocked organizations from deploying the latest Windows updates due to Microsoft Update sync problems.

Additionally, the July 2024 cumulative updates fixed an issue triggered by the June 2025 security updates, which caused the DHCP service to freeze on some Windows Server systems.