After changing your password of your Office 365 account, your credentials used in Microsoft Project also need to be changed.
To fix this:
- Open MS Project
- Open a blank project
- Click the ‘File’ button at the top right (as if you were to save a document).
- Then click ‘Account’, which is almost at the bottom of the menu.
- If the incorrect account is shown, click ‘Switch Account first’.
- Then click the ‘Sign Out’ button for the account you use with Project Server as shown in the picture below.
- Then enter your credentials again when trying to open a project from Microsoft Project Server.
Note: This will not work if you are using the same account to log in to Windows.