edgeAADSTS50196: The server terminated an operation because it encountered a client request loop. Please contact your app vendor.

Got the same problem as everyone else here and no answers to be had.  Can't send email because of client request loop.  Haven't even had Microsoft 365 for a full week.

same problem trying to install the latest update KB4566782.  Microsoft has been no help at all.

After I saw how many of us had this problem I was encouraged to jump down into the Microsoft Help tunnel.  I got referred from a person to a software “Assistant” and after clicking through multiple “suggestions” (Did this help the problem?  No.) I got to a page that told me how to delete my account.  After clicking on for a few more unhelpful suggestions, I decided that starting over from the beginning was the most promising way forward.  The account was only 5 days old, I’d given it out to very few people and it had stopped sending email on the 2nd day.  I _think_ my error may have been in thinking Windows 10 works like Windows Pro. I believe 10 is set up for the home user and certain things designed for “convenience” work differently from my workplace Windows Pro where the Office apps are all separate.  My “client loop” I think was caused by two Outlook accounts that I inadvertenly set up by creating an Outlook email address first in the Outlook app.  Then when I was in Microsoft 365 (as it’s now called) somehow [that’s always a bad word for a computer user] another Outlook account got created with a “name” only a computer would like- mix of letters and numbers.  Hope my experience can help SOMEbody.

Windows mobile Alcatel Lucent Idol 4S with Windows 10 

I had a friend put Google on and my problem is solved ?