I recently tried to sync my iPhone 11 Pro to my Mac (using iTunes on macOS Mojave) and I was told that there was not enough space on my iPhone to fit everything that iTunes wanted to sync. That seemed wrong to me; there should have been plenty of space on my iPhone. The specific error message that iTunes gave me was: The iPhone 'Jeff iPhone Pro' cannot be synced because there is not enough free space to hold all of the items in the iTunes library (additional 85.03 required).
The strange thing was that iTunes was also telling me that my iPhone had about 70 GB in free space more than my iPhone itself was telling me that it had. Why would iTunes think that my iPhone had more free space than my iPhone itself did? And which one was correct?
It turns out that my Mac was correct and my iPhone was wrong. To try to see what was taking up all of the space, and to try to account for the huge discrepancy between what iTunes and my iPhone thought was available for free space, on my iPhone I opened the Settings app, went to General, and then tapped on iPhone Storage. From there, I could see that my TV app was taking up over 140 GB in space, but when I reviewed the files in my TV app there were only about 70 GB in files. In other words, my iPhone somehow thought that my videos downloaded to my TV app were about twice as large as they really were.
The solution was to do a hard reset on my iPhone. How you do this depends upon the model of iPhone that you are using, and Apple has a webpage with all of the instructions. For modern iPhones (from the iPhone X and iPhone 8 and forward), you quickly press and release the volume up button, quickly press and release the volume down button, and then hold down the side button for about 10 seconds or so until you see the screen turn black and then the Apple logo appears, showing that your phone is restarting.
After I did this, my iPhone reported that there was only about 70 GB of videos in the TV app on my iPhone. Also, iTunes on my Mac was happy to sync with my iPhone, now that both my Mac and my iPhone were in agreement on how much space was available.
Whether you encounter this particular bug or something else that you cannot figure out how to fix, the moral of this story is: if all else fails, restart ... and if even that fails, then do a hard restart.
