Seeing the same issue start out of nowhere on our end as well. Previously, this worked fine and our configuration has not changed. JSON is valid and tested by multiple validators. testing in the Apple Validator Tools fails: https://search.developer.apple.com/appsearch-validation-tool testing manually via curl also returns an error: curl -v https://app-site-association.cdn-apple.com/a/v1/domain-name-here.com < HTTP/1.1 404 Not Found < Date: Thu, 10 Dec 2020 20:11:03 GMT < Content-Length: 0 < Apple-Failure-Details: {"cause":"invalid character '\u003c' looking for beginning of value"} < Apple-Failure-Reason: SWCERR00401 Bad JSON content Question for you @Mike_Nedosekin, do you have the apple-app-site-association at the root, or in the .well-known dir?