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// entra id sign-in error · saml single sign-on

AADSTS7500529

What Microsoft says

The value ‘SAMLId-Guid’ isn't a valid SAML ID - Microsoft Entra ID uses this attribute to populate the InResponseTo attribute of the returned response. ID must not begin with a number, so a common strategy is to prepend a string like "ID" to the string representation of a GUID. For example, id6c1c178c166d486687be4aaf5e482730 is a valid ID.

How to fix it

Microsoft doesn't publish a specific fix for this code beyond the description above. This site groups it under saml single sign-on, based on that description, so start with the steps below.

How to investigate

  1. Capture the SAMLRequest from the browser and decode it with the SAML decoder.
  2. Compare the Identifier, Reply URL and requested authentication context with the Enterprise App's SAML settings.
  3. Check the signing certificate is active and matches what the app expects.
  4. Search the sign-in logs for the request ID or correlation ID from the troubleshooting details on the error page.

Tools that help

Common errors: SAML single sign-on

The description is quoted from Microsoft's error code reference. The grouping and investigation steps are this site's guidance.