Dear Sir,
I recently set up a new computer (W's 10 Pro) and immediately began seeing the error message AADSTS50196 whenever I tried to access anything from the help search bar or any Microsoft driven website.
I contacted my computer builder's tech team and got no help. I then did some web research and I gathered that the outlook was grim at best.
I then started to poke about Microsoft's sign in pages etc. Bear in mind I could not create an account and I could not sign in. Through persistence and luck I stumbled onto some account information and it seems that at some point I had created a Microsoft
account and the phone number listed differed from the one I had entered when setting up my new computer. I had a flash of inspiration that this was the source of the problem.
On that page was the option to delete my phone # (password change required) and enter a new number (another password change required). I spent 2 or three hours responding to two texted codes and at least six e-mailed codes to accomplish this.
To verbalize my inspiration is simply that I had two phone numbers attached to the same e-mail address. The Microsoft computer system, when presented with conflicting data will reject both because computer systems cannot, on their own, determine which
is true and which is not true.
I also used the control panel to clear the browser cache because it has better options than MS Edge (I cleared everything.) I also ran disk cleanup to delete as many files as possible.
I am now signing into Microsoft with no problem and I have not seen that error message again.
This may not work for everybody but, I hope will be a building block for a new approach and insight. I hope you can use this to help others with the same issue.