An error has occurred when trying to access IdpInitiatedSignOn.aspx to test SAML authentication on AD FS 4.0 (Windows Server 2016)

So usually one of the first things I do after initially setting up an AD FS environment (among others) is to test the Metadata (navigate to https://your.adfs.server/ federationmetadata/2007-06/federationmetadata.xml which should return valid XML) and sign-in functionality using the IdpInitiatedSignOn.aspx method. For Server 2012/2012 R2 this page enabled by default but if we navigate to this … Continue reading "An error has occurred when trying to access IdpInitiatedSignOn.aspx to test SAML authentication on AD FS 4.0 (Windows Server 2016)"