According to Rockstar, GTA Online is no longer playable on 12Gb PlayStation 3. If you are a 12Gb PlayStation 3 owner you might have noticed that the game has stopped working once with Flight School update.
So, if you want to continue playing GTA Online on your 12Gb PlayStation 3, you have to upgrade your console, or you can still play single-player but only if you’re not connected to the internet.
“If not enough space is available on the system, hardware limitations will prevent players from accessing GTA Online. GTAV Story Mode will still be accessible by playing the game without being connected to PlayStation®Network, and proceeding without additional updates.” said Rockstar.