I have had an app on the apps store for about 4 years. The app uses an API to retrieve some data and displays/manipulates it. The app works for the vast majority of users however, for around 0.01% of users, the first time they open the app after downloading it, the API fails and reports that it cannot retrieve data (it exits elegantly but does not crash). They cannot get the app to work and I have to issue a refund. I cannot repeat the error on simulator or on my test iPhone (13). There is no consistency on IOS or phone model reported. I am guessing that there is some form of configuration that cause the app to fail to retrieve the data. I don't even know where to start to identify the problem. Can anyone point me to some documentation or provide advice as to how I can capture, analyse and fix these rare failures. Thanks