Office 365 webmail and password issue

Hi All,

All of a sudden, all users using webmail now cannot log on the error says:
"Sorry, that didn't work.
Please go back to Office.com and try again.
Thanks."

And some users using outlook now are having the credential window keeps popping up, although they provided the right password.

Something has changed at MS office 365 that I don't know.

Any help/ advice would be appreciated.

Cheers