Several of our readers report that they get the error message that their iDevice/iTunes sync not working when they wanted to create a backup or sync their iDevices. This error often (and annoyingly) occurs when folks get ready to upgrade to the latest iOS and are trying to make a backup BEFORE they update (like we all should as good iOS citizens!)
- Error Message: iTunes could not back up the iPhone because a session could not be started
Try the following tips to resolve your backup problems or when iTunes sync not working:
- Turn OFF WiFi and try syncing or backing up with iTunes
- Turn OFF WiFi syncing from your iDevices to fix the problem. Attempt to sync or backup with iTunes
- Put your iDevice into Airplane mode and then try syncing or backing up with iTunes
- Restart your iOS device, iPad, iPhone or iPod touch by pressing and holding the on/off button for a few seconds and then slide the slider and turn back on
- If restarting does not resolve your issue, launch iTunes with your iPad or iPhone connected to your computer.
- Make sure your iDevice is listed under Devices on the left side of the iTunes window
- From your iTunes menu bar click iTunes / Preferences then select the Devices tab
- If there is more than one backup available, delete all but one. (Consider backing up your backup)
- Restart your iDevice. Press and hold the Sleep/Wake button until the red slider appears
- Slide your finger across the slider to turn off
- To turn iDevice back on, press and hold the Sleep/Wake until the Apple logo appears
- Restart your Mac
- Try to sync now
- If this does not work, try deleting all backups in the iTunes preferences, and then attempt to back up or sync again
- Try right clicking your iDevice in iTunes and selecting “backup,” you will get the error. Quickly “ok” the error. Then select “backup” again, you may get the error a second time. But on the third attempt (do these in rapid succession) of selecting backup, the task initiates and completes. A few readers report success with this multiple attempt method
- Put your iDevice into DFU Recovery Mode
Remember to TURN BACK ON WiFi, WiFi SYNCING, and DISABLE AIRPLANE MODE once you complete your sync or backup via iTunes.
Tips For Windows Users when iTunes sync not working
- Close iTunes
- Then disconnect your iDevice
- Go to start and type in %ProgramData%
- Go to the Apple folder and then navigate to the Lockdown folder
- Delete all the files in the Lockdown folder except the system configuration file
- Restart iTunes
- Once iTunes opens, connect your iDevice
- You should now be able to back up your iDevice
Conclusions
We “fondly” call this particular error the iTunes dreaded syncing problem–and with good reason. It’s very frustrating, and you often need to perform multiple tips to get things working again. Hopefully, a few of the tips listed above worked for you. If you’ve encountered a different fix, please let us know in the Comments. We love to hear from you all and learn more ways to defeat this dreaded iDevice/iTunes sync not working problem! 
And of course, remember to always back up your iDevices via iTunes and iCloud, if possible following our 2X2 rule (2 cloud and 2 local backups.) As this error points out, no one method of backup is 100% all of the time, so best to have multiple backups in multiple places (or in the clouds!)
Related:
- Could not backup because backup file was corrupt or not compatible, fix
- How to back up your iOS device