We have several iOS apps and before uploading them to the appstore we validate them with xcrun altool --validate-app. This works fine on all apps with Catalina but we have (at least) one app that will not validate on Big Sur while the other apps validate just fine BUT when the app is uploaded to TestFlight there are no problems. This can be reproduced on different machines running Big Sur and can pass validation just fine on many different machines using Catalina all using the same network.
The error we see is:
altool[4248:572296] CFURLRequestSetHTTPCookieStorageAcceptPolicy_block_invoke: no longer implemented and should not be called altool[4248:572288] *** Error: Unable to validate archive './artifacts/our_app.ipa'. altool[4248:572288] *** Error: code 1095 (App Store operation failed. Unable to process app at this time due to a general error)
We have tried using the --verbose flag and get a ton of information but have not be able to clearly identify the issue.