Q: Sync session failed to start

Thanks!  It worked just fine!

None of the previous posts worked for me. I ordered a power cord from amazon and was using that when the problem was occuring. I decided to unplug it and replace it with the original cord and it worked.

Worked for me under iOS 7.0.4.  Many thanks!

Thank you! Just tried this and it works perfectly.

This worked for me as well! Thank you very much! Still work!

Rebooting worked for me but had to be done twice.

1. Unplug the iPhone
2. Reboot the iPhone (holding the sleep and home button until the phone resets)
3. Restart the iPhone
4. Restart iTunes
5. Repeat again..

The first time I did it I got the same error, second time worked.

Odd error, hope this helps someone!

Also required a doube reboot but now works for me

This worked on and IPhone 6, IOS 8.1.2, Mac system updated to Yosemite (I believe). Thanks much!

Thanks! Worked like a charm!! 

when im sync my iphone it stuck on contacts can someone help me?!?!?!?!

This worked for me, thanks!

Open up the iTunes menu from the iTunes logo and choose quit, or for quit. Then re-open. Just worked for me. (I already tried a soft reset on my iPhone and turned it off then on again. I don't know if these things added to helping!

four years after the original question and this STILL works...