What to do if I am getting "Error parsing the request, invalid_sp_id..." error in SAML authentication.

[Arpna]

The full error will look this this:

“Error parsing the request, invalid_sp_id: The <Issuer> element MUST be present in <AuthnRequest> element.”

First step is to check if you have used the Setup guide below on the Google side in addition to the Looker Docs:

Looker Cloud Application - Set up SSO via SAML for Looker

We usually get this error message when the SP entity ID is empty and requires a value.
 

You will find more references to the same here:
What means the “SP Entity/IdP Audience” parameter in saml configuration for service provider?

400 saml_invalid_sp_id

I have seen the issue getting fixed once we pass the parameter as described in the document shared above.

Hope this helps!