When you open a file and it shows “Not a valid XMind file”, please note that your file may be corrupted.
Please retrieve a backup from File Cache.
1) Launch XMind for iOS;
2) Enter Settings > File Cache;
3) Tap the backup file of your mind map > Retrieve;
4) Select a location to save the backup.
If the backup cannot work, please send us a feedback from Settings > Feedback.
Please tell us the following information when you send the feedback.
1. Where did you create the file? On XMind for Android, XMind 2020 or XMind 8?
2. Before the file corrupted, what did you do with the file?
3. Please send us the file and we will try to fix the file for you. Please note that if the file become 0KB, we are unable to recover it any more.