Abrupt exits in iOS apps are crashes, which are caused by bugs in the app code. Fixing them is top priority, but to fix them we will need to know why it crashed. Here’s how to help to find the issue:

1. Please make sure your device is sharing crash reports with the app developers. Please enable the ‘Share with App Developers’ analytics option as described in https://support.apple.com/en-us/HT202100. If the option was turned off, please try to make the app crash once more, to make the crash report available to us.
2. If the app is crashing on a particular session, please share the session as .rcz file (from the share button on top of session overview screen) and send it to tracks(at)racechrono.com
3. If the app is crashing for video export or analysis, please also share the raw video files linked to the session, via DropBox, Google Drive or similar, if possible.
4. Write a bug report using the support request form in http://racechrono.com/support/, describing the issue as well as possible, also mentioning your device model and iOS version.