We are trying to upgrade IDP version from v3.4.4 to v5.1.3 and our application is a standalone application. In our application, we had customized the IDP with our external login authentication.
During the upgrade to v5.1.3, we are facing an issue as below,
https://i.sstatic.net/GP30mSDQ.png

When we access our application url, it is redirecting to SP and it is generating an SAML request and sending to IDP (http://localhost:8080/idp/profile/SAML2/POST/SSO).
After this, it is saying as BAD REQUEST with below error,

ERROR:
[net.shibboleth.idp.saml.profile.impl.PopulateBindingAndEndpointContexts:449]

• Profile Action PopulateBindingAndEndpointContexts: Unable to resolve outbound message endpoint for relying party
  ‘http://ipau.sp.sso.manager/sso’: EndpointCriterion
  [type={urn:oasis:names:tc:SAML:2.0:metadata}AssertionConsumerService,
  Binding=urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST,
  Location=http://localhost:8080/SSOSPManager/SSO, trusted=false]
  2024-08-09 17:58:20,090 – 0:0:0:0:0:0:0:1 – WARN
  [org.opensaml.profile.action.impl.LogEvent:94] – A non-proceed event
  occurred while processing the request: EndpointResolutionFailed.

Environment:
Java v17, Apache Tomcat-v10.1.24, IDP v5.1.3

Kindly help me on this to proceed further.
Thank you.