Do this to remove this warning and be able to gain trophies again. This also works if you want to transfer saves from an account to another.
1. Use Vita Save Manager to export the save of the game you want to fix.
2. Open the save in Vitashell and enter the folder sce_sys.
3. Delete everything except sdslot.dat.
4. Open ux0/user/00/savedata and delete the save for the game you want to fix.
5. Import the save again. Even though it the slot may look empty, the save is still there.
6. Run the game!
(7). Export the save again just to have a fixed backup and make Vita Save Manager see the save. (Optional)
@Trev0rDan5 just remove VITASHELL save, no need for any extra steps.
Do this to remove this warning and be able to gain trophies again. This also works if you want to transfer saves from an account to another.
1. Use Vita Save Manager to export the save of the game you want to fix.
2. Open the save in Vitashell and enter the folder sce_sys.
3. Delete everything except sdslot.dat.
4. Open ux0/user/00/savedata and delete the save for the game you want to fix.
5. Import the save again. Even though it the slot may look empty, the save is still there.
6. Run the game!
(7). Export the save again just to have a fixed backup and make Vita Save Manager see the save. (Optional)