WSUS: Microsoft Releases a Manual Fix for Sync Slowdowns and Timeouts

For the past few days, synchronization issues have been affecting WSUS servers, causing slowdowns and even failures when syncing with Microsoft servers. Although the problem is now resolved, there are additional steps you can take to clean up your server. Here is what Microsoft recommends.

As a reminder, WSUS (Windows Server Update Services) is the Windows Server role that centralizes the distribution of Microsoft updates to an organization's workstations and servers. If you're just getting started with this tool, IT-Connect offers a complete course to install and configure a WSUS server. It is a service that Microsoft no longer develops since the announcement that development would stop starting with Windows Server 2025, yet it remains widely deployed in enterprises.

Since Friday, July 17, 2026, administrators have been reporting that their WSUS servers are taking an unusually long time to synchronize. In addition to being slow, synchronization can even fail. The issue is that without synchronization, it is not possible to retrieve the metadata associated with the latest Windows updates through WSUS (or Configuration Manager).

Microsoft first confirmed the issue before deploying an initial workaround in its Cloud. "On July 18, 2026, Microsoft deployed a server-side remediation that restores synchronization timing and normal synchronization operations for new WSUS installations and reinstalls. After this date, newly installed or reinstalled WSUS servers should no longer encounter this issue.", Microsoft states on its website.

Then, on July 20, 2026, Microsoft published a cleanup procedure for servers that were still affected. Let’s take a look at what this means in the rest of this article.

A buildup of test detectoids behind the blocking issues

According to Microsoft, and to use its exact wording, this incident is tied to a service degradation caused by the accumulation of test detectoids published in error to the WSUS channel. Behind this name are objects with titles such as Product Detectoid for ProductName TestProduct%. However, as they accumulate, they overload the metadata database that WSUS must process, to the point of dramatically increasing synchronization times and causing failures.

In its support document, Microsoft also explains that there are impacts on client machines, especially in Windows Update. Several error messages and codes are mentioned, and you may already have seen them if you've had some issues with your WSUS environment.

For example, you may encounter error 0x80244010 (WU_E_PT_EXCEEDED_MAX_SERVER_TRIPS), which indicates that the Windows Update scan exceeded the maximum number of round trips allowed with the WSUS server. Other codes may also appear, such as 0x80244022 (or HTTP 503) when the WsusPool application pool is overloaded, or 0x80072EE2 in the event of a network connectivity issue.

Microsoft's manual cleanup procedure

For servers still affected by these synchronization problems, Microsoft recommends following the instructions outlined in its remediation procedure (KB5121986). It was published on July 20, 2026, in the wake of this incident and applies to all versions of Windows Server.

Looking more closely at what Microsoft is proposing, it quickly becomes clear that this is a WSUS database cleanup. More importantly, the suggested cleanup will permanently delete update metadata. Here are the main steps to carry out:

• Back up each SUSDB database before taking any action, since deletion is permanent.
• Run the cleanup query from SQL Server Management Studio against all SUSDB databases, including those on replica servers. Deletions do not replicate from one server to another, so each catalog must be cleaned individually; otherwise, clients connected to an untreated server will continue to see the test detectoids.
• Let the query remove the incorrect detectoids and set MaxXMLPerRequest to 0. This temporarily lifts the 5 MB limit and helps clients resynchronize properly.
• Once WSUS is stable and clients have synchronized successfully, set MaxXMLPerRequest back to its default value, which is 5242880.

"It may be necessary to limit the maximum number of concurrent connections for the WSUS administration site in IIS, then increase it gradually to allow clients to complete the scan. The goal is to keep IIS CPU usage at around 80%.", Microsoft notes.

Once cleanup is complete, the vendor recommends reindexing the SUSDB database, running the WSUS Server Cleanup Wizard, and then running IISReset or recycling the WsusPool application pool to clear the catalog cache. So you have work to do on the WSUS server side, while things should proceed normally on the client side (otherwise, check the WindowsUpdate.log file).

Have your WSUS servers been affected by these synchronization slowdowns?

Florian Burnel Co-founder of IT-Connect

Systems and network engineer, co-founder of IT-Connect and Microsoft MVP "Cloud and Datacenter Management". I'd like to share my experience and discoveries through my articles. I'm a generalist with a particular interest in Microsoft solutions and scripting. Enjoy your reading.

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