Our website is requiring IEMode in Edge Chromium and our user is using SSO. When they log in from their SSO log-in URL, their Edge Chromium browser opens up our website (user access URL) in IEMode as expected but they are getting an error in authentication.
From our user's SSO log-in, the request type our website is receiving is GET so we are getting the error “Failed to receive SAML response by HTTP post”, we are expecting an http posted SAML data. Developer Tools does not work on IEMode so tracing stops right before IEMode page loads.
As instructed by https://docs.microsoft.com/en-us/deployedge/edge-ie-mode-sitelist#configure-neutral-sites, we have tried including the SSO login domain to the EMIE sites list with open-in as None but we still get the same result. If we change the open-in as IE11 (same as our website's), it works. This just is not an option our user wants to use (setting login domain to open in IE11) as our user has other apps that use SSO and require to be not in IEmode.
Is there a header or IIS setting we can change, or another Edge Chromium browser setting or even registry setting we can modify, to work around this Edge Chromium-to-IEMode SSO issue?