I'm glad that solved it for you, but I will echo again that at least some of the folks on this thread are using a build machine that we do not manage, and one that is supposed to be a completely blank slate whenever we run a build. Therefore, I don't believe cert or provisioning profiles being cached is the issue that some of us are being faced with. It is tough to tell if that is even the issue that anyone is facing, since the issue doesn't happen every time. It only happens SOME of the time.

That is definitely not the issue all of us are having. I can't speak for everyone, but in my case, I am using Azure DevOps and Fastlane on a hosted build machine. There is nothing on the machine until I run my build, and it downloads the one cert it needs. There are no other certs on the machine when the build runs. Hopefully Apple keeps trying to find an actual solve for this, because that is not the correct one.

Interestingly enough, we have had it failing randomly since Monday. I thought today it was finally completely broken. We had 2 builds in a row rejected this morning. The last 3 have gone up fine, though. Can Apple give us an update on this? It is obviously not something that all of us are doing wrong. Our build process signs the same way, with the same cert EVERY time. This is clearly on their end.

We have also been having the same issue intermittently since Monday, June 1st. Most of our builds have submitted fine, but several have failed due to the signing error. We are also using fastlane in a CI build, but nothing has changed, and our certs are not expired. Today, we have had multiple builds in a row, so it may have gone from intermittently broken to permanently broken. Any information about this would be greatly appreciated.