iOS: 'Not enough free space' alert when trying to sync

Products Affected

iPad, iPhone, iPhone 3G, iPhone 4, iPod touch, iPod touch (2nd generation)

Symptoms

When attempting to sync content to an iOS device over USB or Wi-Fi^*, iTunes may not transfer data with the iOS device. iTunes may also display one of these alerts:

"iPhone cannot be synced because there is not enough free space to hold all of the items in the iTunes Library (additional space required)."

"iPod touch cannot be synced because there is not enough free space to hold all of the items in the iTunes Library (additional space required)."

"iPad cannot be synced because there is not enough free space to hold all of the items in the iTunes Library (additional space required)."

Resolution

There could be several reasons why this could occur. Start with Solution 1. If the issue continues, try Solution 2 and, if necessary, Solution 3.

Solution 1

In the case of iOS device becoming physically disconnected in the middle of syncing music, podcasts, videos or photos, it's possible that orphaned files will be left on the iOS device. This can prevent iTunes from syncing the iOS device on subsequent sync sessions.

One symptom of this issue will be displayed in iTunes where the Capacity indicator for the iOS device will report a large amount of "Other" disk usage for the device. To resolve this issue:

Turn off the music or photo sync option in iTunes for the device.
Click Apply to sync the changes to the device.
Turn the music and photo sync options for the device on again.
Click Apply again to try to sync the device to iTunes.

Solution 2

Try turning off the automatic syncing functions for the iOS device. To do this:

Select the iOS device under Devices on the left side of the iTunes window and click the Summary tab.
Deselect "Automatically sync when this device is connected" and select the "Sync only checked songs and videos" checkbox.
Click Apply to sync the changes to the device.
Reduce the amount of data that is being synced to the device and resync the device. For example, if syncing your Music library exceeds the memory capacity of the device, choose "Selected playlists" to transfer rather than "All songs and playlists" under the Music tab in iTunes.