I am having storage issues with my Samsung Galaxy S Duos. I solved it by moving apps from phone memory to the SD card, so now 1.2 GB of internal space is free. However, it still tells me that I have insufficient storage for apps.
I found that there are 94 MB of cache files there, but even if that's the case I should still have plenty of free space. Why does my phone still think that the internal storage is full?
See What can I do to manage my phone's internal storage? and install the app DiskUsage. On my phone, it made clear that the system itself takes up 1.2 GB, while this is not shown in the overview (settings > storage).
A possible explanation for why you get a message that internal storage is full, is that Android always keeps up free space equal to the size of the largest app you installed. So if you install the XyzApp that takes up 100MB, android wants 100MB free disk space in case it needs to update and download the new version.
You can try to move as many apps as possible to your external sdcard. That frees up space, and if by accident the biggest app can be moved, android will need less free space.
Hope this helps!
(And thanks to Izzy!)
