Removing the Entitlements.plist did solve the "Validation failed (409)" error, but my app was still crashing on launch in TestFlight. I had to add None to my csproj file to stop the launch crash, which means there is some kind of linker issue, but I haven't been able to narrow it down any further yet.

Hi @DTS Engineer, thank you for your reply. I've removed the entitlements.plist entry. Could you help confirm if it is expected that in my distribution provisioning profile "In-App Purchase" is ticked, but greyed out in it's "Capabilities" so I can't edit it? Also, before I added the entitlements.plist I was able to successfully use Transporter on my Mac to send my IPA file to App Store Connect. However, when I tested the app using TestFlight it was crashing on start every time. I've got the crash file, but I'm not sure it's very helpful (I've attached it). Is the any help of guidance you can give for figuring out why it's crashing? It works perfectly locally in debug/release mode. symbolicated.crash Thanks, Ben