Hi Lord,
Thank you for posting your problem, I am here to help you today. insufficient storage space, file corruption, lack of save permissions, or software conflicts.
To fix this problem try this steps:
Check your Mobile storage.
Check your Excel access permission on your Android device.
Try to save a copy check if still getting the same error.
Reinstall the Excel application on your Android device and check if it can save or still getting the same problem.
Let me know how this goes. Looking forward to helping you out. If you need more help please feel free to let me know.
Best regards,
Jansher