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If the authentication request is returned without a SAMLResponse parameter, it means that the sign-on process failed or was interrupted. it seems the application is not using HTTP redirect binding when sending the SAML request to Microsoft Entra ID. Could you please check the callback URL where you are using an IDP-initiated URL not the SP-initiated URL? the IdP also needs to know the callback URL in order to send the SAML response to the correct location.
Could you please check that the SAML toolkit is properly configured with the correct values for the SAML endpoint, issuer, and certificate which has not expired.
I hope this information helps! please Feel free to ask any questions you may have.
Thanks,
Akhilesh.
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