Microsoft just confirmed two new known issues in recent updates for Windows 10 on the official Windows 10 Updates History website.
April 2019 has not been very kind to Microsoft even though everything looked as if Microsoft would be right on track to improve update quality. The company announced that it would postpone the release of the next feature update of Windows 10 to the end of May 2019 to give it another round of testing in the Release Preview ring.
Everything went down in flames on the April 2019 Patch Day. Administrators and users noticed that Windows 7, Windows 8.1, and Windows Server machines were freezing after installation of the updates that Microsoft released on that day for these operating systems.
Microsoft acknowledged the bug after some time and confirmed that the freezes happened on devices with certain antivirus solutions installed.
Windows 10 and Windows Server 2016 / 2019 appeared fine at this point. Microsoft acknowledged two new known issues caused by updates for these operating systems recently, however.
Only KB4493509, the update for Windows 10 version 1809, causes both known issues while the updates for previous versions of Windows 10, only one.
The issue that affects all devices is limited to devices in business environments for the most part as it requires that Cluster Shared Volumes are used.
Microsoft notes that certain operations may fail under certain conditions:
Certain operations, such as rename, that you perform on files or folders that are on a Cluster Shared Volume (CSV) may fail with the error, “STATUS_BAD_IMPERSONATION_LEVEL (0xC00000A5)”. This occurs when you perform the operation on a CSV owner node from a process that doesn’t have administrator privilege.
Microsoft suggests to run the operations from processes with administration privileges or from nodes that don't have CSV ownership. Microsoft is working on a fix for the issue and plans to include it in upcoming releases.
Windows 10 version 1809 is affected by another issue, and it is antivirus related. According to the patch notes, systems with ArcaBit antivirus software installed may become unresponsive on start after update installation.
Microsoft and ArcaBit have identified an issue on devices with ArcaBit antivirus software installed that may cause the system to become unresponsive upon restart after installing this update.
ArcaBit is a Polish software developer that focuses on security software. The company operates its own line of security software including several antivirus products.
The issue appears to be restricted to ArcaBit software; Microsoft does not mention Avast, Sophos, or certain other antivirus products which suggests that the issue could be different from the one that users experience on earlier versions of Windows.