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

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

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

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

I was having the same problem. Out of all the suggestions here the only thing that worked for me was to keep my phone plugged in and restart my computer. When iTunes automatically launched it started syncing on its own. Thanks guys

Well in my case I'd change the ''Microsoft'' to ''Apple''. Their latest ios is as useful as a frozen banana. (It seems to be a Vista type fiasco.)

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. 

On you iPhone, force close all the Apps in the multitask window.

Follow these steps to force an app to close:

1. From the Home screen, click the Home button twice.
2. Tap and hold on the app.
3. When it starts to jiggle, tap the to close it one by one until all cleared

Now do a Soft reset of your iPhone:Hold both Home and Sleep button for around 10secs until you see the Apple logo then release. After it returns to Home screen, connect to sync and see if this resolves the issue.

thank you this hlepped a lot

Thanks for all the steps to try.

Syncing  works fine for all items except for one. this is a private recording, it was a wav.  , downloaded from dropbox...that I converted to mp3 under File, convert  to new version.  This mp3 is over 3 hours, does size matter on a sync?  I was wondering because I also converted with a downloaded program that synced a copy, the only problem was the voice logo every 30 seconds that interups the recording.

                                                Thanks

                                                new iPhone user

                                                      steve

Works for me. Thanks.

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

None of these solutions worked for me. I am running iTunes as an Administrator, as suggested previously. Then I had to completely shut down and restart everything again. Then I had to enter my password to unlock the ipad which let the syncing begin.

I've tried about everything I can find on the internet and I still can't sync my MSoutlook 2013 to my iPhone. My PC crashed and I had to resintall most of my software including MS Outlook 2013 and iTunes. Prior to the reinstall, I could not synch iPhone to my MS outlook 2013 without any problems.

I think the problem may be at the stage when iTune and MS outlook tries to communicate.

ITunes unchecks the "sych contacts oulook" and "sycn calendar with oulook" buttons when the synch button is pressed.

This is what I am running:   Windows 8.1, IOS 7.1.2, iTunes 11.3.1.2, Ms Outlook 2013 locally installed on my laptop

This is what I've done. The "-" is the result.

1. Run as administrator                                                      -done. Didn’t work
2. Msoutlook addins                                                            -All modules enabled and installed.
   1. itune outlook addin
   2. outlook change notifier
3. ran scanpst.exe.                                                               -Seems okay. Didn’t work
4. Stop zonealarm                                                                -didn’t work
5. Check read write access right.                                    -Seems Okay. Didn’t work
   1. C:\Users\USER\AppData
   2. C:\Users\USER\AppData\Roaming
   3. C:\Users\USER\AppData\Roaming\Apple
      Computer\SyncServices\Local\TFSM
6. Run network connectivity test on iTunes (under Help menu).
   1. Test results

1. Deleted lockdown folder                                              -Didn’t work
2. Deleted                                                                        -Didn’t work
   1. C:\Users\USER\AppData\Roaming\Apple
      Computer\Logs\MobileSync
   2. C:\Users\USER\AppData\Roaming\Apple
      Computer\MobileSync
3. Uninstall in the following order:                                -Didn’t work
   1. iTunes
   2. Apple Software Update
   3. Apple Mobile Device Support
   4. iCloud
   5. Bonjour
   6. Apple Application Support
4. Reset Iphone to factory setting                                 -Didn’t work

WORK ! thx

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