Microsoft first released the Windows 10 build 10856 (more popularly known as Threshold 2), the November update and version 1511 last Nov. 10. The update came with improvements for bundled services and the operating system's user interface (UI). However, it got temporarily delisted from public distribution due to a glitch that resets data collection and privacy settings. It was once again made available on Nov. 24 but with limited installation options.

Regardless of the hiccups, most Windows 10 users are now running on version 1511. But after a couple of weeks, complaints have begun to surface. One common issue users are complaining about is how the update removes certain antivirus apps.

"After an update my Bitdefender anti-virus was stopped," Redditor supernoodles2011 says. "I went into list of programs (or apps now) and it wasn't there either then went looking in the Programs folder and it was removed from there as well while the Windows 10 firewall kicked in."

He says he had to redownload the antivirus installer and find his activation key to get the app back up and running. According to the Redditor, he was using the premium BitDefender version. 

Other users report experiencing the problem on the free version of BitDefender while others say that they have had no problems with their BitDefender AVs even after the Threshold 2 update. 

Other users say that while their BitDefenders weren't affected, certain applications were removed.

"It removed a Gigabyte program that I was using to control the CPU fan speed. CCleaner too," says another user, noting that Microsoft should at least check and warn userrs about certain programs that will be removed after the update gets installed.

The case is not just isolated to BitDefender. Users of Spybot Search and Destroy and certain versions of Nod32 also complain about their antivirus software getting removed after the Threshold 2 update.

Microsoft is yet to comment on the issue.