Antivirus is ESET, but behavior is same with it enabled or disabled.
(minor update) Windows is 21H1 Version 10.0.19043 Build 19043
When turning any third-partys antivirus program off, Windows Defender will automatically turn on! So, also turn the Defender off, and keep it open, and keep an eye on it, because seconds later, it will turn back on again - turn it off again-again, and it will then be turned off. Do that before trying to update your computer once again-again.
When updating HOPEFULLY, is succeded, first turn on Windows Defender. Then, turn on your ESET-antivirus. Windows Defender will then turn off automatically - and keep turned of...