How to Resolve Duplicate Username Errors When Logging in with SSO (Single Sign-On) in Salesforce

公開日: Mar 25, 2026

タスク

You want to resolve a duplicate username error that is preventing a user from logging into Salesforce using Single Sign-On (SSO).

ステップ

Go to Setup (the gear icon in the top right, then select Setup).
In the Quick Find box, type 'Users' and select 'Users' under 'Administer'.
Find the user experiencing the issue. You can search by username or email.
Check the 'Username' field for the user.
If the username is duplicated, change it to a unique value. Salesforce usernames must be unique across all Salesforce organizations.
Alternatively, if the duplicate username is intentional (e.g., for different orgs), ensure the SSO configuration correctly maps to the unique Salesforce user IDs, not just usernames.
Verify your Single Sign-On settings by going to Setup, typing 'Single Sign-On Settings' in the Quick Find box, and selecting it.
Review the 'Federation ID' setup for the affected user. The Federation ID in Salesforce should match the unique identifier sent by your Identity Provider (IdP).
Ensure that your Identity Provider is sending the correct and unique identifier for the user.
If changes are made to the Federation ID in Salesforce, inform the user to try logging in again.
If the issue persists, review the SSO login history for more details on the error. Go to Setup, type 'Login History' in the Quick Find box, and select it.

ナレッジ記事番号

005226726

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