F-Droid v1.15.2: archive.newpipe.net/fdroid/repo: Error getting F-Droid index file => null All other repos didn't create errors

I'm trying to add the custom F-Droid repository, and when I do I am getting this error? > archive.newpipe.net/fdroid/repo: Error getting F-Droid index file => null All other repos didn't create errors. What am I doing wrong? I've tried a few times always the same thing. Each time I remove the repo. How can I resolve this error?