Microsoft Resolves Windows Server Boot/Freeze/Performance Issues in Latest Update

In a critical turn of events last month, a security update intended for Windows Server 2019 systems inadvertently introduced startup issues, crashes, and performance deficits.

IT administrators were quick to notice a dramatic decline in server performance, rendering systems nearly inoperable, following the installation of the KB5041578 update. Microsoft confirmed that this patch was the culprit behind the introduced anomalies.

Upon investigation, Microsoft identified the root cause as a directory enumeration issue, particularly when scanning the %systemroot%\system32\catroot2 folder, leading to an endless loop of incorrect path enumeration. This resulted in slowed server operations, unresponsiveness, and abnormally high CPU usage—especially noted within encryption services.

While Microsoft did not specify the antivirus software at fault, discussions among IT administrators pointed fingers at background processes related to Microsoft Defender, suggesting an internally generated issue.

Affected servers exhibited the following symptoms:

• Significant increase in CPU usage
• Higher disk latency and utilization
• Deterioration in OS and software performance
• Failure in the startup of encryption services (CryptSVC)
• Black screen occurrences upon system startup
• Extremely slow system boot times
• System freezes or crashes

Given the severity of these issues and the impracticality of waiting a month for a fix, Microsoft opted for an immediate resolution using Known Issue Rollback (KIR) technology. This approach allows for specific updates to be rolled back automatically via Microsoft servers, requiring no system reboot—only an active internet connection for the automatic fix deployment.

With the September security update, Microsoft has now thoroughly addressed these concerns, providing IT administrators a sigh of relief that the update will not bring about the previous headaches. However, whether this latest update introduces new issues remains to be seen, humorously noted by the community. 😂