| When a user account with the email address already exists in GitLab, but the user does not have the SAML identity tied to their account. | The user will need to [link their account](#user-access-and-management). |
### Message: "SAML authentication failed: Extern uid has already been taken, User has already been taken"
### Message: "SAML authentication failed: Extern uid has already been taken, User has already been taken"
1. Save your changes. For reference, you can view [an example configuration in the troubleshooting reference](../../../administration/troubleshooting/group_saml_scim.md#azure-active-directory).
NOTE: **Note:** If you used a unique identifier **other than**`objectId`, be sure to map it instead to both `id` and`externalId`.
NOTE: **Note:** If you used a unique identifier **other than**`objectId`, be sure to map it to`externalId`.
1. Below the mapping list click on **Show advanced options > Edit attribute list for AppName**.
1. Below the mapping list click on **Show advanced options > Edit attribute list for AppName**.
1.Leave the `id` as the primary and only required field.
1.Ensure the `id` is the primary and required field, and `externalId` is also required.
NOTE: **Note:**
NOTE: **Note:**
`username` should neither be primary nor required as we don't support
`username` should neither be primary nor required as we don't support