ADFS error after upgrading from ADFS 2.1 to 4.0
Looks like you are running into issue in https://blogs.technet.microsoft.com/pie/2016/10/23/adfs-2016-cannot-addupdate-relying-party-from-the-gui-from-metadata-files/
Looks like you are running into issue in https://blogs.technet.microsoft.com/pie/2016/10/23/adfs-2016-cannot-addupdate-relying-party-from-the-gui-from-metadata-files/