Idp Initiated login results in 404


Close to complete an integration between our MVC .NET CORE application and OKTA, using SAML. The login flow works perfectly when it is SP (application side initiated)

However, when the flow is Idp initiated (ie , the user clicks on the icon on OKTA dashboard) we get a 404 when redirecting to the MVC controler.

Here you have a screenshot of the 404

If I just hit enter in the url, it goes to the controller and all works well. It is just the redirect from OKTA’s link not working.

Any ideas?