If the UK ETA app is crashing while you are trying to check the confirmation code, follow these steps to troubleshoot and potentially resolve the issue:

1. Restart the App: Close the app completely and reopen it. This can resolve minor glitches causing the crash.

2. Update the App: Ensure you have the latest version of the UK ETA app. Check the App Store for any available updates and install them.

3. Clear App Cache: If you're using the app on a system that allows cache clearing, try clearing the app’s cache. This action can remove any corrupted data that might be causing issues.

4. Reboot Your Device: Sometimes, simply restarting your device can help clear temporary files and free up resources, which may fix the crashing issue.

5. Check Internet Connection: Make sure you have a stable internet connection. A weak or intermittent connection can cause the app to crash when it attempts to verify the confirmation code.

6. Check for System Updates: Ensure that your iOS is up to date. Go to Settings > General > Software Update to check for and install any available updates.

7. Reinstall the App: If the app continues to crash, consider uninstalling it and then reinstalling it from the App Store. This can clear any potential software bugs.

8. Contact Support: If none of the above solutions work, reach out to the UK ETA support team for further assistance. This can often be done through their official website or customer service contact options.

9. Look for Known Issues: Sometimes, issues may be widespread. Check forums, such as Reddit, or official updates from the UK government regarding app functionality or known issues - learn more - learn more.

By following these steps, you should be able to troubleshoot the crashing issue you are experiencing with the UK ETA app while checking the confirmation code. If the problem persists after trying all available solutions, contacting support is your best option.