I'm having the same issue as well.I use OneLogin with SAML2, and my scenario is below.
1) I have two websites configured with OneLogin utilising Component Space.
2) When I am redirected to the first website ("It authenticates and provides user which is login send that username") after logging in to the second website using onelogin ("Without login directly provide user which is active current cookie "), operating properly in localhost
3) After deploying the modifications in the development environment using the correct URL and onelogin configuration
4) Right now, if I try to log in on the first website, everything works great. However, if I try to move to the second page, I receive the problem below. If I log in on the first website with the same user, however,
on that console if i click 2 website working fine
Now i am confused where is the error An SP-initiated SAML response from was received unexpectedly.