Not able to decode Autho IDP saml response

I am using auth0 as just the idp , my service provider gives me this error message after getting the saml response :
User authentication service auth0: Failed to process SAML Response: Unable to decode base64 in POST binding message.

Which service provider are you using? Are you able to share the SAML response here with any sensitive details removed? This would help greatly in diagnosing the problem.