Xamarin iOS builds crashing on startup after iOS upgrade

Jonathan Cook 6 Reputation points

I have an app that has been working fine in production and on Testflight. However, recently our customer upgraded to iOS 15 and the app started crashing for them on startup. I looked into this and was able to reproduce the crash by deploying directly to a device. The cause of the crash ended up being related to the Microsoft AppCenter Crash Analytics Nuget package we were using. The problem related to some namespaces, that were protected by iOS, being used by the Microsoft Analytics package. The fix was simply to upgrade the package and after deploying to the device I was no longer able to reproduce the crash.

However, when I uploaded the build to Testflight the app still crashes on startup. Since I am unable to debug or even get past the splashscreen I cannot get any useful logs or crash reports. I have the iOS crash log but it is not particularly useful since it only states there was an unhandled xamarin exception. I will post the crash here anyways, in case someone can make sense of it.

I have since tried a myriad of things to try and resolve this issue. One of which being removing the MS Analytics package entirely from the project. Another being upgrading all of the nuget packages in my app to their latest version.

There are old versions of the app that do not crash on Testflight, but when I revert my code back to those version commits and build/upload to Testflight those new versions crash on startup. This leads me to believe there is something wrong with my build setup (I use a windows machine connected to a Mac to build). However, I can build other apps with the same setup that do not crash. I am at a loss!

So in summary:

  • Has anyone experienced this issue or something similar? And what did you do to fix it?
  • If no one has experienced this, can someone at least give me some troubleshooting tips?

Thank you in advance!


A Microsoft open-source app platform for building Android and iOS apps with .NET and C#.
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