The file cannot be loaded due to a DLC conflict in the save file.

[azilunia_03]

A friend of mine was playing the game using the Steam Family Sharing feature, and he liked it so much that he bought it.
However, due to a conflict with the P4G OST, which is a pre-purchase benefit, the previously played game file does not run. Is there a solution?

[Arifufu]

there is no a solution, that save file can be loaded ONLY with P3R steam copy that has P4G BGM DLC

[Ratirefure]

You might be able to edit the broken save file, but it sounds like you (someone with the DLC) need to load the save in your game, change some values, and save the game and send it back to the person without the DLC.

https://www.reddit.com/r/PERSoNA/comments/1beao9p/p3r_pc_remove_dlc_requirements_to_load_save_files/

Good luck

EDIT: Your friend can also use your copy to launch the game, if you're using the new Steam Families.