Why do I get an 'insufficient storage' error when trying to install apps when I have sufficient storage? When I try to install anything through the Play store, I get a pop-up saying I have 'insufficient storage', with a button which takes me to view my current used storage. According to that program, I have 449mb free on my internal storage. Infuriatingly, I am not told how much each app actually requires, but 449mb should be enough to install anything, since the hungriest app I currently have installed only uses ~250mb.

I managed to get enough space to install the 1.5mb 'Move to SD card' app I wanted. Now that app reports that I have 'no reason to move to SD card, since it shares the same disk with the OS'. In that case I do not just have 449mb free; I also have the 16gb free on my SD card which it should be able to use to install new apps.

Why then does it still complain that it does not have enough space?
25 MB free internal storage is minimum requirement (source: TechniPages, AndroidCentral). If free space falls below that, the "insufficient storage" error is triggered.
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Why does my phone keep telling me it has low storage?
Not enough storage on android device