Hi there! I’m sorry to hear you're having trouble logging into the Lufthansa app on your phone with a technical error. To help you better, could you please tell me:

- What type of phone you’re using (Android or iPhone)?
- Have you tried logging in via a web browser on your phone or a computer, and if so, did you face the same issue?
- Did this problem start recently or has it been ongoing for a while?

Meanwhile, I can guide you through some common steps that often resolve such login issues:

1. Clear app cache and data:
- On your phone, go to Settings > Apps > Lufthansa app.
- Tap Storage, then select Clear Cache and Clear Data. This can remove corrupted temporary files causing the error.

2. Update or reinstall the app:
Make sure your Lufthansa app is updated to the latest version via the App Store or Google Play. Otherwise, try uninstalling and reinstalling it.

3. Check your internet connection:
Try switching between Wi-Fi and mobile data to see if the issue persists.

4. Try using a different browser for authentication (if the app redirects you to one for login):
Some users found setting Firefox as the default browser helped with login issues.

5. Restart your phone: A simple restart can sometimes resolve temporary glitches.

If you’ve already tried these or if the issue continues, please let me know. We can then delve deeper like checking for account locks due to failed attempts or trying alternate login methods.

Are these steps something you can try now? Or do you want me to guide you through any specific step?