Q: what is error code 1439

Hi lenshao,

Thanks for using Apple Support Communities. Based on what you stated, it sounds like the iPod is getting a 1439 error. I would recommend that you read this article, it may be able to help the issue.

iPod: Can't restore or update in iTunes with error 1415, 1417, 1418, 1428, 1429, 1430, 1436, or 1439 - Apple Support

Cheers,

Mario