*** Workaround Solution - Follow Steps Below ***I finally heard back from Avast Senior Support after my case was escalated. They provided some recommendations to try excluding a few Microsoft domains (too many of them I thought). I did some testing to narrow things down and I ran Wireshark and I figured out the following...
To me this fix although it does work should be seen as a band-aid temporary fix. I let Senior Support know that they should pass this along to the software developer team to fix so that this manual configuration is not required. This is affecting users that don't even realize that the cause is Avast's handling of HTTPS scanning.
Steps to fix OneNote sync issue with Avast Web Shield HTTPS Scanning- Open Avast AV and go to ☰ Menu ▸ Settings. Select General ▸ Exceptions, then click Add Advanced Exception* ▸ Website/Domain
- Type in URL path *.onenote.com
- Click Add Exception button to save this configuration
- Notice new http and https exceptions for OneNote domain listed
- Close Avast AV and test OneNote syncing
* It is important to select
Add Advanced Exception and not the basic Add Exception button as that will not work for the required URL. This seems to be a bug that I've reported. If you don't follow my exact instructions, you'll end up with a file/folder exception instead of Website/Domain exception. This only happens if you use a short URL with one dot. If you want to instead use the longer more specific URL that I list below then you can simply click on the basic Add Exception.
See attached screenshots of the above steps for added reference (you need to be logged into this forum to see attachment screenshots).
![Tongue :P](https://forum.avast.com/Smileys/default/tongue.gif)
I don't know why I didn't run Wireshark sooner to figure this out. It's all right there...the specific URL is
contentsync.onenote.com if want to add that exception instead of the global asterisk variable. This will likely work until Microsoft decides to use a different URL to sync and then this will break again. This is why Avast should find a more permanent solution. 112 days for the community of users to get a mediocre solution.
![Angry >:(](https://forum.avast.com/Smileys/default/angry.gif)
I hope that Avast doesn't drop the ball on this and that they find an out of box internal permanent fix so that uninformed users do not fall victim to this issue.