Solution 1 : Reset the login settings for Outlook
The solution you can try is resetting the login settings for Outlook through Windows Credentials Manager. In order to do that, please follow the steps described below:
- Go to Control Panel and click on Credentials Manager
- Navigate to User accounts and go to Credential Manager
- In the Windows Credentials and Generic Credentials section, remove any stored credentials referencing the Office 365 or ms.outlook email addresses
- Click on Details and choose Remove from vaults
- Click yes on the warning box
- Repeat the steps until you remove all of the credentials associated with your email address
Solution 2: Check credential settings
If the first solution did not work out for you, you could also try to verify if the option Prompt for credentials is not checked in profile as this could be another cause for this message keeping to pop out. In order to check this:
- Start Outlook and go to File
- Choose Account settings in the Account settings section
- Select your exchange account
- Click the Change button and go to More settings
- Select the Security tab
- Under the user identification, make sure the Always prompt for logon credentials option is not selected
- Click OK and restart Outlook