If you are experiencing the issue where the Umax face scan gets stuck at 91%, here is a comprehensive step-by-step approach to troubleshoot and hopefully resolve this problem:

1. Restart the Umax Application:
Close the Umax app and restart it. Sometimes, a simple restart can resolve minor glitches.

2. Restart Your Device:
If restarting the app does not work, try rebooting your device. This can help refresh system resources.

3. Check for App Updates:
Ensure that your Umax app is updated to the latest version. Go to the app store on your device and check for any available updates.

4. Clear Cache and Data:
- For Android users: Go to Settings > Apps > Umax > Storage > Clear Cache and Clear Data. This will reset the app to its original settings.
- For iOS users: You may need to uninstall and then reinstall the app to clear the cache.

5. Adjust Camera Settings:
Ensure that your camera is functioning properly and that there are no obstructions or issues affecting the camera quality.

6. Change Scanning Environment:
Ensure that you are in a well-lit environment when scanning your face. Poor lighting can impact the quality of the scan.

7. Reinstall the Umax App:
Uninstall the app and then reinstall it from the relevant app store. This can help fix any underlying issues in the app’s installation.

8. Check for Device Compatibility:
Confirm that your device meets the requirements to run the Umax app, specifically regarding the camera and software version.

9. Seek Technical Support:
If the issue persists after trying all the above steps, consider reaching out to Umax support. They may have additional troubleshooting steps or information about current status on any server issues.

10. Refer to Online Community Forums:
Sometimes other users face similar issues and may have found solutions. Checking platforms like Reddit or Tech Support Guy can provide insight from community experiences - learn more - learn more - learn more.

Following these steps should help you resolve the issue of the Umax face scan getting stuck at 91%. If none of these solutions work, it may indicate a more complex technical issue that requires professional help.