If you see an message after an update, your Game Data (not your save) is likely corrupted.
If your main save is corrupted, you can sometimes trigger a restore by deleting the primary save file from the PS3's [Save Data Utility] menu; the game may then prompt you to load the internal backup. Manual Backups: You can copy your main save to a FAT32-formatted USB drive for safe keeping. Save Locking and Transfer gran turismo 6 save data ps3