A couple of weeks ago I noticed that whenever I tried to login to my Office 365 account, my password kept being rejected until eventually I’d get an error that says:
“401 - Unauthorized: Access is denied due to invalid credentials” (despite entering the correct password).
After looking into it, I realized that the only way I could successfully login was if I disabled Avast shields control.
What’s up with that? Is there a way to continue using Avast in a way that won’t prevent me from using Office 365? I have no choice, I have to use it for work, so if there’s no way to get around this I’ll have no choice but to choose a different antivirus software.
I did two things, not sure which fixed it. I turned off web shield, and entered site fine. then found the following, added them and turned web shield back on. Still had access.
Resolution 2: Firewall or proxy servers require additional authentication
To resolve this issue, configure an exception for Office 365 URLs and applications from the authentication proxy. For example, if you’re running Microsoft Internet Security and Acceleration Server (ISA) 2006, create an “allow” rule that meets the following criteria:
Allow outbound connections to the following destination: *.microsoftonline.com
Allow outbound connections to the following destination: *.microsoftonline-p.com
Allow outbound connections to the following destination: *.sharepoint.com
Allow outbound connections to the following destination: *.outlook.com
Allow outbound connections to the following destination: *.lync.com
Allow outbound connections to the following destination: osub.microsoft.com
