Update chaos after patch day: WSUS server refuses synchronization

After Windows Patch Day in July 2026, reports of problems with the Windows Server Update Service (WSUS) are increasing. Microsoft has now confirmed a glitch that is causing slow syncs and timeouts.

Update chaos feared after patch day

Updates are currently only available with delays or can no longer be accessed at all. As a result, administrators are increasingly reporting failed synchronizations. According to the company, all supported Windows client and server versions are affected. There are error messages in the log files of those affected that indicate interrupted communication. The connection to several IP addresses through which Microsoft distributes its updates is failed, they say.

Since patch day, administrators have reported similar observations and increasing problems. As a result, the connection stopped and no updates could be synchronized since then. Currently, data traffic between the local WSUS instances and the Microsoft servers seems to have largely come to a standstill for many. What is noticeable is that the problem occurs regardless of the server version used. Microsoft explained that the cause was an “accumulation of publishing metadata.”

Solution is in progress

The group is working on a solution; Performance should improve as server-side repairs are completed and rolled out, which has been the case since July 18th.

Mitigation: Microsoft released a mitigation for this issue on July 18, 2026. Synchronization times and synchronization processes on WSUS servers have been restored and are functioning normally for newly installed WSUS installations and rebuilds. This mitigation prevents newly installed or rebuilt WSUS servers from encountering this issue. James Cole

For WSUS servers that were previously affected, Microsoft is working on mitigation steps to help customers safely remove the affected metadata from their environments. Further information will be provided as these instructions become available. Microsoft names the following versions as affected:

Affected platforms

Some administrators also reported that the sws.update.microsoft.com page could not be accessed at times. Whether this is related to the same disorder or has another cause remains unclear. Microsoft has announced that it will gradually repair the affected systems and provide an update as soon as possible. Anyone who is also affected or has already been able to fix the problem is invited to share their experiences in the comments. Any feedback helps to better classify the disorder.