Hi! Thanks for reaching out about the nickname change issue in Dog Sim Online. The error "sErrorString1001" usually indicates a problem recognizing the name input on the server side.

Since you have already tried simple names and restarting, let's try a few more steps:

1. Make sure you’re connected to a stable internet connection, as the game needs to communicate with the server to update your nickname.

2. Double-check if the nickname you want follows the game’s rules — no special symbols, spaces, or offensive words. Sometimes the server rejects names that don’t meet those criteria.

3. Clear the game cache on your Android device:
- Go to Settings > Apps > Dog Sim Online.
- Tap on Storage.
- Then tap 'Clear Cache'.
Restart the game and try to change your nickname again.

4. If that doesn't help, try logging out of your game account and logging back in to refresh your profile data.

If these steps don’t solve the problem, it might be related to a temporary server issue or a bug. In that case, contacting the game support directly at [email protected] is a good next step, as they can check your account specifically.

Would you like me to guide you through clearing the cache on your Android device or do you want to try the network and name rule checks first?