After putting compatibility hold on devices running old versions of Realtek Bluetooth Radio drivers, Microsoft has now blocked certain PCs from updating to Windows 10 November 2019 Update that are running old AVG and Avast (both free and paid antivirus products) and incompatible Qualcomm WiFi drivers.
While the latest Avast/AVG antivirus version available is 19.8, if you now try to update to Windows 10 November 2019 Update from Windows 10 May 2019 update with AVG/Avast version 19.5 or earlier running, you’ll receive a warning from Windows 10 Setup to uninstall the antivirus. Both Avast and AVG recommending to reinstall the latest versions of theirs if you’re affected.
Microsoft noted on the Windows v1909 release information page that there are issues with “some older versions of AVG and Avast anti-virus products. ”
The company says ” Microsoft and Avast has identified compatibility issues with some versions of Avast antivirus and AVG antivirus. Any application from Avast or AVG that contains antivirus version 19.5.4444.567 or earlier is affected.”

If you’re running old driver versions of Qualcomm WIFI adapters you’ll be denied from installing Windows 10 1909 by showing a warning, which asks it needs your attention by highlighting the problem with “Qualcomm wifi driver” your PC has: “your PC has a driver that isn’t ready for this version of Windows 10. A new version is available please go to aka.ms/qcamain10_4_0_2 to learn more”

Microsoft notes cause for the blocking November 2019 Update here and offers a workaround with detailed instructions.
Microsoft has identified compatibility issues with some driver versions for certain Qualcomm Wi-Fi adapters. Devices with affected driver versions might experience loss of Wi-Fi connectivity after updating to a newer version of Windows 10.
To safeguard your upgrade experience, we have applied a hold on devices with affected Qualcomm driver from being offered Windows 10, version 1809, Windows 10, version 1903, or Windows 10, version 1909, until the updated driver is installed.
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