Q: when iphone 4s update then error 29

Hey there tausiffromdehri on some,

I understand that you are trying to update your iPhone and are getting an identifiable error code. This error code and information pertaining to it can be found in this article:

Check for hardware issues

If you see error 53, learn what to do. If you see one of the errors below, you might have a hardware issue:

• 1, 3, 10, 11, 12, 13, 14, 16
• 20, 21, 23, 26, 27, 28, 29, 34, 35, 36, 37, 40, 56
• 1002, 1004, 1011, 1012, 1014, 1667 1669

Here's what to check:

1. Make sure that you have the latest version of iTunes.
2. Check for issues with third-party security software.
3. Make sure that your USB cable, computer, and network are reliable. Then try twice more to restore your iPhone, iPad, or iPod.
4. If you still see the error message, you can check for outdated or modified software or contact Apple support.

Get help with iOS update and restore errors - Apple Support

https://support.apple.com/en-us/HT204770

Thanks for using the Apple Support Communities. Have a good one!