I've been looking at Identity server 4 (idsrv4) just to have a play with it.
This runs on .NET Core which I something else I need to get up to speed on.
There is also a WS-Fed plug-in which I got working and tried to hook up to ADFS as an exercise.
The metadata endpoint is:
and when I tried to import this into ADFS, I got the normal:
"Metadata contains some features not supported by ADFS" warning.
Now this could be because the metadata contains a SAML profile that ADFS doesn't support - PAOS being an example.
But 999 out of 1000 times, it's because the endpoints are "http" not "https".
Looking at the metadata, this is indeed the case.
This means that although the entry is added to ADFS, it has no endpoints so it will never work.
You can't just edit the metadata because it's signed and you'll get a signing error when you try and import the updated file.
You can delete the whole "Signature" section in the XML if you want. Do this at your own risk - normal best practice security applies :-).
The other way is to update the metadata when it's generated. There is no metadata file - it's dynamically generated every time.
You can do this in the "Properties".
Select the "Enable SSL" check box. IIS Express generates a new endpoint as above so now you have to replace all the instances of:
with the https endpoint as above.
This also means that you need to change this address in any of the client samples.
The new metadata imports without issues.