Why has my tablet switched from downloading apps to the device to trying to DL them to my SD card?

[AC Question]

I have a Samsung Galaxy Tab 4, and prior to today it was downloading and installing apps to my device with no trouble. Suddenly, today (5/6/2015) it has decided to try and download apps to my SD card, which we all know does not work. It will download the whole thing but then give me the error message "Can not install to USB or SD storage device" (or something like that). I did not change any settings, I keep the device cleaned up with Clean Sweep. I turn it off at night and back on again in the morning. I delete apps I am no longer using on a regular basis. The memory is less than half full. I unmounted the SD card and downloaded & installed my app, then remounted the SD card, which worked, but why did I have to do it this way when, prior to today, it was downloading apps to the device and ignoring the SD card? I have been using the SD card to save files & pics for months, so it is not that it was unmounted or anything. WTF? Anyone else with this problem?? Anyone know why the sudden change in my tablet? Thanks for any help or advice!

 

[B. Diddy]

Welcome to Android Central! I see that error mentioned from time to time. Some apps will automatically move some data to the SD card in the process of the installation, so the error might be related to this process. The reason you haven't seen it before might be because other apps you've installed don't do this on installation (or the SD card had more free space back then). How full is the microSD card?