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troubleshooting-saml-authentication.md

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title shortTitle intro versions type topics redirect_from
Troubleshooting SAML authentication
Troubleshoot SAML SSO
If you use SAML single sign-on (SSO) and people are unable to authenticate to access {% data variables.product.github %}, you can troubleshoot the problem.
ghes ghec
*
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how_to
Accounts
Authentication
Enterprise
Identity
Security
SSO
Troubleshooting
/admin/identity-and-access-management/using-saml-for-enterprise-iam/troubleshooting-saml-authentication

{% ifversion ghes %}

About problems with SAML authentication

{% data variables.product.prodname_ghe_server %} logs error messages for failed SAML authentication in the systemd journal logs for the github-unicorn container. You can review responses in this log, and you can also configure more verbose logging.

For more information about SAML response requirements, see AUTOTITLE.

Configuring SAML debugging

You can configure {% data variables.product.prodname_ghe_server %} to write verbose debug logs for every SAML authentication attempt. You may be able to troubleshoot failed authentication attempts with this extra output.

Warning

  • Only enable SAML debugging temporarily, and disable debugging immediately after you finish troubleshooting. If you leave debugging enabled, the size of the logs increases much faster than usual, which can negatively impact the performance of {% data variables.product.prodname_ghe_server %}.
  • Test new authentication settings for {% data variables.location.product_location %} in a staging environment before you apply the settings in your production environment. For more information, see AUTOTITLE.

{% data reusables.enterprise-accounts.access-enterprise %} {% data reusables.enterprise-accounts.policies-tab %} {% data reusables.enterprise-accounts.options-tab %}

  1. Under "SAML debugging", select the drop-down and click Enabled.
  2. Attempt to sign into {% data variables.location.product_location %} through your SAML IdP.
  3. Review the debug output in the systemd journal for github-unicornon {% data variables.location.product_location %}. For more information, see AUTOTITLE.
  4. When you're done troubleshooting, select the drop-down and click Disabled.

Decoding responses

Some output in the systemd journal for github-unicorn may be Base64-encoded. You can access the administrative shell and use the base64 utility on {% data variables.location.product_location %} to decode these responses. For more information, see AUTOTITLE.

To decode the output, run the following command, replacing ENCODED_OUTPUT with the encoded output from the log.

base64 --decode ENCODED_OUTPUT

Error: "Another user already owns the account"

When a user signs into {% data variables.location.product_location %} for the first time with SAML authentication, {% data variables.product.github %} creates a user account on the instance and maps the SAML NameID and nameid-format to the account.

When the user signs in again, {% data variables.product.prodname_ghe_server %} compares the account's NameID and nameid-format mapping to the IdP's response. If the NameID or nameid-format in the IdP's response no longer matches the values that {% data variables.product.github %} expects for the user, the sign-in will fail. The user will see the following message.

Another user already owns the account. Please have your administrator check the authentication log.

The message typically indicates that the person's username or email address has changed on the IdP. Ensure that the NameID and nameid-format mapping for the user account on {% data variables.product.prodname_ghe_server %} matches the user's NameID and nameid-format on your IdP. For more information, see AUTOTITLE.

Error: Recipient in SAML response was blank or not valid

If the Recipient does not match the ACS URL for {% data variables.location.product_location %}, one of the following two error messages will appear in the authentication log when a user attempts to authenticate.

Recipient in the SAML response must not be blank.

Recipient in the SAML response was not valid.

Ensure that you set the value for Recipient on your IdP to the full ACS URL for {% data variables.location.product_location %}. For example, https://ghe.corp.example.com/saml/consume.

Error: "SAML Response is not signed or has been modified"

If your IdP does not sign the SAML response, or the signature does not match the contents, the following error message will appear in the authentication log.

SAML Response is not signed or has been modified.

Ensure that you configure signed assertions for the {% data variables.product.github %} application on your IdP.

Error: "Audience is invalid" or "No assertion found"

If the IdP's response has a missing or incorrect value for Audience, the following error message will appear in the authentication log.

Audience is invalid. Audience attribute does not match https://YOUR-INSTANCE-URL

Ensure that you set the value for Audience on your IdP to the EntityId for {% data variables.location.product_location %}, which is the full URL to your instance. For example, https://ghe.corp.example.com. {% endif %}

{% data reusables.saml.current-time-earlier-than-notbefore-condition %}

{% ifversion ghec %} {% data reusables.saml.authentication-loop %} {% endif %}