Recipient endpoint doesn't match with SAML response

I don't know why is your problem occurring randomly, but at least one way to fix it is by configuring SAMLContextProviderLB instead of your current SAMLContextProviderImpl.

The SAMLContextProviderLB is typically used to tell Spring SAML public about the public URL used on a reverse proxy or load balancer, but in this case you can use to force Spring SAML to think it's using HTTPS. You can find details in chapter 10.1 Advanced Configuration of the Spring SAML manual.

You should also make sure to properly set property entityBaseURL on your MetadataGenerator bean, because without doing so the generated metadata will depend on whether you made first request to your application using http or https. Again, all of this is documented.

I had the same problem with Spring Security SAML. So i had to change the contextProvider from SAMLContextProviderImpl:

  @Bean
  public SAMLContextProviderImpl contextProvider() {
      return new SAMLContextProviderImpl();
  }

to SAMLContextProviderLB:

  @Bean
  public SAMLContextProviderLB contextProvider() {
    SAMLContextProviderLB samlContextProviderLB = new SAMLContextProviderLB();
    samlContextProviderLB.setScheme(scheme);
    samlContextProviderLB.setServerName(serverName);
    samlContextProviderLB.setContextPath(contextPath);
      return samlContextProviderLB;
  }