iphone could not be synced because the sync session failed to start

I had the same problem. I am running iTunes 11.0.0.163 on Windows 7 64bit. Thanks for all who've posted suggestions. This is what I did and it fixed the problem:

1) closed iTunes

2) configured iTunes to Run as Administrator

3) unplugged the iPhone from USB

4) plugged iPhone into USB

Windows automatically launched iTunes.

The phone now syncs fine.

Just made one very simple move without having to restore iPhone or reinstall iTunes.. 🙂

1st step:http://support.apple.com/kb/TS1538 *Read 'in my case' in here first before following this link*
Follow that link to restart (or if necessary) reinstall your Apple mobile device support.

In my case, Leave iPhone connected all the way. I first exit iTunes. Then i stopped the Apple Mobile device support (by following a part on that link above in step 1) which Effectively made my iPhone undetectable on itunes but discoverable by windows as a 'camera device'. Then while device is still connected, i started the Apple mobile dev support again. Now i open itunes and there my iPhone re-appears.

2nd step: After your iphone re-appears on iTunes, press Sync and all is well... 😉

P.S, Mine is iPhone 4 running on iOS 5, iTunes 10.5, Windows 7..

I found this to be the case with me too, I tried all the suggestions, but with the latest software 7.0.3, I had forgotten to say "trust" on my pop up message on my phone, and without trusting my computer my phone wouldn't sync. Once I clicked "trust" on my phone for my computer, it synced just fine.

I had the same problem which I fixed by doing a combination of things. Step 1 - Right click on iTunes and select 'run as Administrator'. Step 2 - Select 'Authorize this computer' option from the 'Store' menu. Step 3 - Right click on the phone listed under 'Devices' and select 'Transfer Purchases'. This way I was able to sync all the apps I had on my iPhone 4S and see them in iTunes.

This solved my problem too: I just quit iTunes and relaunched, sync started successfully on iTunes start up. (OSX 10.68)

Shutting down your phone (while still connected and with iTunes closed) then turning it back on worked for me.

If, by chance you are running windows 7 or Vista, try starting itunes as an administrator. I had the same problem, solve by running itunes as administrator. I respect Apple, however this lack of attention to detail is very out of character. Is all character dead?

Exiting iTunes, without disconnecting or ejecting the iPhone, and relaunched the iTunes application fixed syncing. I had tried ejecting then reattaching the cable, restarting the computer, soft reboot on the phone, etc...

exit itunes without unplugging and then open itunes again. if this doesnt work, uncheck apps & photos, sync again, before finish syncing stop it, then check it again.

just upgraded from 4xx to 5.0.1 and saw this - worked for me too, exiting and restarting itunes (leaving phone plugged in to my Mac). thanks!

Like ArrrJay - I'm running Vista and had to run iTunes as an administrator (right click on the shortcut and select "run as administrator")

None of these solutions worked for me, but I restarted my iPhone and that worked!

Thanks "mrmcmena". Its working fine after restart my iPhone.

Only this worked for me as well: All I did was exit itunes and open it again. It began syncing automatically.

All I had to do was restart my iphone and then the sync worked.