How to Set Default Domain in Microsoft Office 365 (O365)
Oct 6, 2025
Okta Integration Network
Okta Classic Engine
Okta Identity Engine
Overview
When attempting to federate a domain with the Okta O365 app, the following error message is observed:
Federating to the 'Default' domain is not allowed
This article will discuss why this error is displayed and how to resolve the error.
Applies To
- Microsoft Office 365 (O365)
- Default Domain
- Single Sign-On (SSO)
Cause
The domain being federated is configured as the default domain.
Solution
The domain being federated can not be configured as the default domain. To resolve the issue, promote a different domain as the default domain.
To promote a domain as the default domain:
- Log in to the Office 365 tenant.
- Click the Microsoft 365 admin center > Navigation Menu > Show All > Settings > Domains.
- Click on the three dots located next to the domain to be promoted to the default domain and select Set as default.
