I got a new Samsung Galaxy S10 phone, I transferred my data and settings from my old phone using Samsung Switch. This appeared to work OK but I could not connect the Outlook mobile app or OneDrive mobile app to my Office 365 account.
I raised a support call on Microsoft and got a call back within 20mins. The technician told me
“Office 365 authentication is performed by the default browser on the phone. It looks like you are having a caching problem”.
- we proved this hypothesis by opening an incognito window and logging in successfully.
The solution to this problem was to uninstall Samsung Internet and use Chrome. However, I note that although I had updated the phone after I powered it up this was after I had used Samsung Switch which runs during the “first use experience”.
When you unbox a new phone you must run the firmware upgrades until you are running the current version. This took 4 hours on my phone after doing a hard reset. Only then should you use Samsung Switch or install Microsoft 365 applications.
If you have repeated authentication errors (and have verified your username and password are correct) then try uninstalling your default browser and setting Chrome to be your default.