This means that, yes, if apps become briefly inaccessible you surly must have been already warned by your iPhone that disk space is running out. Only when you ignore this warning and still continue to perform actions that put additional strain on the storage, like updating App Store apps, iOS attempts this method of last resort to accommodate your new software.
What Can I Do?
The only common sense action from your end is to start freeing up storage in order to avoid situations that push your disk space to the maximum. iPhones that always operate under low storage condition can also become a little slower than normal.
So, start deleting unnecessary apps, transferring photos and videos or perform one of the 20 tips provided here for freeing up space on your iOS device.
The iOS Auto-Cleaning Trick
Sadly Apple isn’t currently offering a button that allows you to manually free-up space by asking iOS to clean cache and temporary files. However, you can trigger auto-cleaning by using a workaround. Your iPhone’s storage doesn’t need to be as low as only a few MB left, you can trick iOS that you are willing to purchase a movie from iTunes. Select one that is very large over 2GB, like the “Captain America: Civil War” for example. Do make sure, that your available storage is lower than the size of the file that you want to purchase. iOS will initiate the auto-clean process in order to finalize the sale for Apple.
Tip: When the Cannot Download warning opens up, tap on Settings and if you browse to General -> Storage & iCloud Usage you should notice how your Available value has increased with a few hundreds of MB. Stop completing the purchase and that’s it!
Fact: Do you know what a blue dot next to the app icon name on iPhone Home Screen means?