Android sets apart about 400MBs for application data in a seperate partition for dem purposes, if tthis gets filled you will likely get an error like this, to check the space left on this partition, I think you go to settings, about, then storage(not too sure as I'm kinda new to Android. There. May be a way to reformat in order to get more apparently space but I'm not sure...

I may be wrong in all this, but it seems the most likely to me.