What causes AADSTS75001?

SAMLRequest sent over the wrong binding (e.g. HTTP-POST while Entra ID expects HTTP-Redirect, or vice versa). Incorrect encoding of the SAMLRequest — missing DEFLATE compression for Redirect binding, or invalid Base64. Malformed or truncated SAMLRequest parameter (URL-encoding issues, query string cut off by a proxy). Required SAML fields missing or in the wrong order (Issuer, Destination, AssertionConsumerServiceURL). Service Provider metadata in the Enterprise Application doesn't match what the app actually sends (Reply URL / Identifier mismatch)

How do I fix AADSTS75001?

Capture the raw SAMLRequest using a SAML tracer (browser extension) or Fiddler and decode it — confirm whether it's well-formed XML after Base64/DEFLATE decoding. In the Entra ID portal → Enterprise applications → your app → Single sign-on, verify the configured Reply URL (ACS) and Identifier (Entity ID) exactly match the values in the SAMLRequest. Check the binding: HTTP-Redirect requires DEFLATE + Base64 + URL-encode; HTTP-POST requires Base64 only. Mismatch is the #1 cause of this error. Update the application's SAML library or SP configuration to send a compliant AuthnRequest (Issuer, Destination = Entra ID SSO URL, valid ID and IssueInstant). If the app is third-party, share the captured SAMLRequest with the vendor and reference Microsoft's SAML protocol requirements — the SP needs to fix it, not Entra ID

Low severityauthentication

Power BI Error:
AADSTS75001

What does this error mean?

Microsoft Entra ID (Azure AD) could not deserialize the SAML message because the binding or encoding is invalid.

Common causes

1SAMLRequest sent over the wrong binding (e.g. HTTP-POST while Entra ID expects HTTP-Redirect, or vice versa)
2Incorrect encoding of the SAMLRequest — missing DEFLATE compression for Redirect binding, or invalid Base64
3Malformed or truncated SAMLRequest parameter (URL-encoding issues, query string cut off by a proxy)
4Required SAML fields missing or in the wrong order (Issuer, Destination, AssertionConsumerServiceURL)
5Service Provider metadata in the Enterprise Application doesn't match what the app actually sends (Reply URL / Identifier mismatch)

How to fix it

1Capture the raw SAMLRequest using a SAML tracer (browser extension) or Fiddler and decode it — confirm whether it's well-formed XML after Base64/DEFLATE decoding
2In the Entra ID portal → Enterprise applications → your app → Single sign-on, verify the configured Reply URL (ACS) and Identifier (Entity ID) exactly match the values in the SAMLRequest
3Check the binding: HTTP-Redirect requires DEFLATE + Base64 + URL-encode; HTTP-POST requires Base64 only. Mismatch is the #1 cause of this error
4Update the application's SAML library or SP configuration to send a compliant AuthnRequest (Issuer, Destination = Entra ID SSO URL, valid ID and IssueInstant)
5If the app is third-party, share the captured SAMLRequest with the vendor and reference Microsoft's SAML protocol requirements — the SP needs to fix it, not Entra ID

Frequently asked questions

What does AADSTS75001 mean?

An error occurred during SAML message binding.

How do I fix this error?

Check your application registration, token configuration, and user permissions in the Azure portal. Review Conditional Access policies if the error is policy-related.

Source · learn.microsoft.com/en-us/entra/identity-platform/reference-error-codes#aadsts-error-codes