Hi @rahul-asati
Welcome to the Auth0 Community.
An invalid thumbprint error does suggest a change in the certificate either on the connection (you’ve already mentioned this has not changed) but it may have changed on the IdP end. Check the connection’s configured certificate and compare with the IdP’s certificate sent in SAML response - either from a HAR file (network tab on the browser dev tools) or tenant logs if debug mode is enabled - one of the certificates may be expired, or one of the parties involved has rolled over their certificate.
You can also review this related community post for more information https://community.auth0.com/t/saml-sso-invalid-thumbprint-error/91165
Please get back in touch with us if you need further information.
Warm regards.