403 Sorry Access denied error when a user tries to sign in to Outlook Web App in Microsoft 365

Original KB number:   2988732

Symptoms

When a user tries to sign in to Outlook Web App in Microsoft 365, the user receives an error message that resembles the following:

403
Sorry! Access denied :(

The page may not be available or you might not have permission to open the page. Please contact your administrator for the required credentials. For new credentials to take effect, you have to close this window and log on again

Cause

This issue may occur if the MyBaseOptions user role is not enabled in the Default Role Assignment Policy.

Resolution

To resolve this issue, follow these steps:

1. Sign in to the Microsoft 365 portal.
2. Select Admin, and then select Exchange to open the Exchange admin center.
3. Select permissions, and then select user roles.
4. Double-click Default Role Assignment Policy.
5. In the Default Role Assignment Policy window, make sure that the MyBaseOptions check box is selected under Other roles, and then select save.

More information

For more info about permissions in Exchange Online, see Permissions in Exchange Online.

Still need help? Go to Microsoft Community.