Azure AD Error AADSTS900236: The SAML Authentication Request Property 'Subject' is not Supported and Must not Be Set

When passing the Subject claim in an AuthnRequest to Azure AD, the following error is returned:
AADSTS900236: The SAML authentication request property 'Subject' is not supported and must not be set.

• Azure AD (Entra ID)
• Subject Claims
• AADSTS900236

This happens because Azure AD does not support Subject claim in the AuthnRequest. See the Microsoft documentation Subject for more information

Remove the Subject tag from the SAML request template because Azure AD does not support this tag from being sent.
Passing a login_hint to Azure using a SAML connection is not supported.