ADFS connection error "IdP-Initiated login is not enabled for connection"

Problem statement

We have a new ADFS connection created. We saw the below error when testing login.

"description": "IdP-Initiated login is not enabled for connection \"CONNECTION_NAME\".

Solution

The ADFS connection type does not support IdP-initiated flows. Instead, you will need to set up a generic SAML connection and point the ADFS server at it. The below doc explains the steps:

And then enable IdP Initiated as per the documentation here for your new SAML connection: