Users facing issues in login for the ServiceNow Classic app. SSO neither worked on mobile not desktop.
Issue with communication protocol.
Issue with access protocol. IdP has mandate the secured protocol https, which was http.
In the instance, the IdP record is updated with "https" protocol in place of "http".
All the URLs in the IdP url, are moved from http to https, SSO is working.
IdP has made the connection secured, so it is mandate to use HTTPS for the URL in IdP configuration in instance.