Why won't my Samsung Galaxy Ace let me update my apps? Why won't my Samsung Galaxy Ace let me install updates? It lets me download, but then when it gets to installing it says: 


  could not be installed on USB or SD card
It might be possible that you have a previous version with support for 'move to SD card' installed on your SD card but the update removed that support.

Thus it fails because replacing the app on the SD card is not allowed any more.

Try to move the culprit to the phone storage in advance and retry.