How to fix Microsoft 365 login problems

Read the error before you touch anything

Microsoft sign-in errors are more specific than people assume, and the difference matters. "Your account or password is incorrect" is a credential problem. "We didn’t hear from you" is multi-factor. "Your account has been disabled" is an administrator action, not something the user can solve.

Resetting a password against a multi-factor problem wastes ten minutes and changes nothing. Read first.

If the password is being rejected

1. 1Try signing in at office.com in a private or incognito window. This rules out a stale cached credential, which is a common cause on a machine that has had a password change.
2. 2Check the keyboard language and Caps Lock. Obvious, and still a real cause.
3. 3Have an administrator reset the password rather than guessing at old ones. Repeated wrong attempts can trigger a lockout and turn a small problem into a bigger one.
4. 4On Windows, clear saved Microsoft credentials in Credential Manager. An old saved password there keeps re-submitting itself and can lock the account repeatedly.

If multi-factor authentication is the blocker

This is the most common cause we see in practice, and the trigger is almost always a new phone. The authenticator app does not move across with a normal phone backup, so the person has their password, their email and their laptop — and no way to approve the prompt.

1. 1Check whether the person recently changed or reset their phone.
2. 2If they still have the old device, register the new one from it before wiping the old one. This is by far the easiest path and it closes once the old phone is gone.
3. 3Otherwise an administrator has to reset the multi-factor method for that user, after confirming who they are by some means other than email.
4. 4Set up a second method — an alternate phone number or a backup code — at the same time, so the next phone change is not another outage.

If it is the licence or the account itself

1. 1In the Microsoft 365 admin centre, check whether the user still has a licence assigned. Licences get reassigned during staff changes and it is easy to take one from the wrong person.
2. 2Check that the subscription itself is paid and active. An expired card disables mailboxes across the whole organisation, and the reminders go to mailboxes that are now disabled.
3. 3Check whether the account has been blocked from signing in. This is a switch an administrator sets, often correctly during offboarding and occasionally on the wrong account.