iTunes Unable To Backup iPhone Whenever I try to backup my 128 GB iPhone 6s, I get an error 


  iTunes could not back up the iPhone 'Talon's iPhone 6s' because not enough free space is available on this computer.


While my internal SSD doesn't have enough space, I have my iTunes Library on an external HD which has 1.32 TB free. I have made sure that the library is in fact on the external drive by selecting it by holding the Option key when launching iTunes.

Any ideas on how to fix this?

PS: iTunes 12.4.1.6, OS X 10.11.5, iOS 9.3.2
The default location for iPhone Backups is:

$HOME/Library/Application Support/MobileSync/Backup


If the Macintosh HD doesn't have adequate free space and or adequate free space cannot easily be made available at the default location, then the following can be used as a workaround.

First, if the iPhone is showing in iTunes eject it, then close iTunes.

If you have existing backups at the default location you can first copy the existing Backup folder to a new location on a different drive/partition/volume that has adequate free space.

Once you've copied the Backup folder to a new location you can either delete the original or rename it, e.g.: Backup.old. This needs to be done to allow for the creation of a symbolic link to the new location of the MobileSync Backup folder and the symlinks name also needs to be "Backup".

To create the symbolic link, it Terminal, use the following command line example while changing the path to what's appropriate for your use.

ln -s /Volumes/&lt;Your External HDD&gt;/MobileSync/Backup ~/Library/Application\ Support/MobileSync/Backup


With the symbolic link created you can now open iTunes, connect the iPhone and perform a backup.