Q: I never set up a passcode，why I'm always asked to input a passcode before update the new version?what should I do?

Hey there Charming Guy,

It sounds like you are getting a prompt for a passcode before you can update your device. This sounds like a restrictions passcode from what you describe. You can disable it in your settings by entering the code here:

iOS: Understanding Restrictions (parental controls)

http://support.apple.com/kb/ht4213

1. Tap Settings > General.
2. Tap Restrictions.
3. Tap Enable Restrictions and enter a passcode. You can use the passcode to change your settings or turn off Restrictions. If you lose or forget your Restrictions passcode, you will need to perform a factory restore to remove it.

Thank you for using Apple Support Communities.

All the very best,

Sterling