It is very important that you run the latest, most updated version of your Anti-Virus package on Windows, and in most cases we would recommend that you run the latest, most updated version of Microsoft Windows. So when it turns out that two huge anti-virus companies tell their users not to update to the latest version of Windows, it's concerning.
Microsoft works closely with security software developers, so it's surprising that McAfee and Avast warn users not to install certain versions of their products on PCs running the latest software.
Here's what McAfee (owned by Intel) said in a blog post:
WARNING: Intel Security has worked closely with Microsoft to ensure that McAfee security software and hardware products are fully compatible with Windows 10 Anniversary Edition endpoints. However, do not upgrade to the Windows 10 Anniversary Update without first verifying whether your McAfee product is compatible.
Avast offered a similar warning but said most users haven't had issues with the update.
If you run either versions of these anti-virus programs, you can choose to either not run the latest version of Windows, or else change your Anti-Virus software. We recommend AVG and offer big discounts for anyone who has a paid-for license of any of the other Anti-Virus packages.