sync session failed to start

I have the same issue. I have spent several hours on the phone with an Apple tech and still no fix. VERY frustrating. Apple says it's the first that they have heard of this issue but obviously it is an issue. My wife has a iphone 4 and it syncs fine with the same computer. I have tried all these things plus Apple gave me a new phone thinking it was a hardware issue but it still doesn't work. I would love some more help on this issue.

Thanks

I've tried this and still didn't work.

Thank you! Finally! Not only did you help me with this problem about failing to sync, but I also was able to sync custom ringtones on my iphone 4s, which I've been trying for hours! Thank you very much!

using itunes 10.6.1 on a mac, there is no "reset sync history" so just:

Open iTunes --> Preferences --> Devices

Delete the backup

Close iTunes

Open iTunes and start Sync.

*i imagine this happened because yesterday i deleted the 1000+ photos and videos off my phone, freeing 3GB of space.

thank you.

I've got exactly the same issue for three weeks now that just came out of nowhere.

Running Windows XP, all updates, all the latest IOS and iTunes software updates.

Can backup the phone but cannot sync. It seems to be able to get data off the phone but can't put data onto the phone.

"The iPhone [name] is unable to sync because the sync session failed to start."

Have been struggling for three weeks with no resolution. Have spent countless hours trying to get to the bottom of it and tried everything imaginable. Phoned Apple customer support and spent an hour and a half on the phone with them yesterday without progress. Apple people, though very polite and professional, have told me the issue is not one they have seen before. (obviously they don't talk to each other or share the same databases!)

Have:

1. Removed and reinstalled ALL Apple software including iTunes
2. Restarted phone
3. Reset all settings on phone
4. Deleted backups
5. Reset sync history
6. Deleted Lockdown folder
7. Different USB port
8. Different cable
9. Created new user account on computer
10. Changed the time zone on the computer and reset (one Apple forum suggested that this was a possible fix)
11. And probably half a dozen other things that I've forgotten by now.

Need a resolution to this soon as I've now probably wasted at least 6 hours and managed to get nowhere and can't manage my schedule from my iphone any longer.

I've also done all the above. I've had this issue going on for over two months now.

I'm in Ireland, so not sure who I can call! I've run diagnostics on Itunes and it's telling me that the sync is working fine, but then it refuses to start.

It's very frustrating. Music and back-up works fine over iCloud, but I've not been able to copy a film onto my phone for months!

It's an issue. I've tried every suggestion I can find - nothing fixes this. That must be a standard-practice put-off if they have an issue that can't be fixed - "I/We haven't heard of this this problem before."

Yeah, right.

https://discussions.apple.com/search.jspa?peopleEnabled=true&userID=&containerTy pe=&container=&spotlight=true&q=sync+session+failed+to+start

Did you try this?:

Open itunes--> Edit--> Preferences--> Devices

Delete the backup

Reset sync history

Close itunes

Open itunes, then File--> Sync

I had the same issue as you and once i did this, i finally was able to sync

>>

Did you try this?:

Open itunes--> Edit--> Preferences--> Devices

Delete the backup

Reset sync history

Close itunes

Open itunes, then File--> Sync

I had the same issue as you and once i did this, i finally was able to sync>>

Yep, still no joy. Interestingly, in consult with Apple tech rep on phone today, plugged my old iPhone 3G in and it worked fine on the same iTunes account. So, it's something to do with either the 4s or the IOS software.

FYI, my iTunes diagnostics also shows no errors and says all Sync Tests passed successfully.

Thanks, that worked perfectly. 🙂

Deleting the backups, resetting sync history, and restarting iTunes worked perfectly for me. Thanks!

Well, this is interesting (but not very helpful in understanding what caused it.) -- Plugged the phone in last night and it synched perfectly -- without having done anything to it or to iTunes for three days.

There must have been some sort of automatic software update applied that has fixed it.

Also interesting, at some point somehow there were thousands of appointment entries made in my Google Calendar (all exactly the same -- blank, all-day appointments and beginning last Thursday and lasting until the year 2127, and synched to the calendar on my iPhone, somehow without a valid sync session taking place--and now they are all gone, without me doing anything.

At least everything seems to have returned to normal now (except that iTunes tells me that my phone is synched with "another" installation of iTunes and will erase all my music on the phone if I synch with this iTunes Library...)

This worked for me, thanks!!

I recently had this problem and i fixed it. If you have a mac, just click on itunes, then preferences, then devices, then delete your back up. After you delete it, quit your itunes, then reopen it. It should sync without any issues. It worked for me, if it doesn't work for you, then I'm sorry.

Worked for me, too. Using 10.6.3.25 on Windows 7. Not sure why I randomly had this issue all of a sudden, but it's working now!

Thanks! 🙂