Microsoft's Windows April Patch Tuesday Updates Claim More Antivirus Conflict Victims

Few things are more annoying than when a Windows update wreaks havoc on your system. It's a case of the cure being worse than the disease, as Ray Stevens sang about in his comical song "Doctor Doctor (Have Mercy On Me)." We saw this play out recently when it was reported that a Patch Tuesday roll out was causing boot problems on some systems with certain antivirus software installed, and the list of affected AV software appears to be growing.

Image Source: Flickr via Rory Finneren

Originally, Microsoft only said that the update was conflicting with some machines that have Sophos Endpoint Protection installed. Sophos also acknowledged the problem, saying it had received reports of PCs failing to boot, and recommended that users boot into Safe Mode to uninstall several updates as a temporary fix. Those updates include KB4493467, KB4493446, KB4493448, KB4493472, KB4493450 and KB4493451.

As it turns out, the Patch Tuesday package is conflicting with other third-party AV software as well. One of them is ArcaBit, a lesser known AV solution.

"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," Microsoft states in a support document. "We are presently investigating this issue with ArcaBit and will provide an update when available."

ArcaBit is also recommending that affected users roll back recent updates, depending on which version of Windows they are running. They include:
  • Windows 10: KB4493509 (or KB4493464 and KB4493441)
  • Windows 8.1: KB4493446 and KB4493467
  • Windows 7: KB4493472 and KB4493448
In addition, Microsoft has blocked the affected April updates from installing on Windows 7 and Windows 8.1 systems that are running AV software from Avira, and has started issuing updates to the fix issues with machines running Avast for Business, Avast CloudCare, and Avast Business Edition.

It's not clear exactly why the Patch Tuesday updates are causing certain systems with third-party AV software to barf, or exactly how widespread the issue is—there are a gazillion AV solutions out there. On the bright side, though, fixes are starting to roll in.