Failed to Save
Failed to save error fix...
- Important! Right-click on One Piece Pirate Warrios 4 in steam - Manage - Browse Local Files - Right-click on OPPW4.EXE - Properties - Compatibility - Check *Run this program as administrator* and click Apply. Now start your game via steam until you get the *Failed to save* error.
Now you have to go to C:\Users (or whatever your Windows drive letter is), there you will certainly find a very strange folder (mine was Ïîëüçîâàòåëü) which will contain *AppData* folder, and if you dig deeper you will find *Local* folder and then, finally - *BANDAI NAMCO Entertainment* folder.
Now all you have to do is to copy that *BANDAI NAMCO Entertainment* folder over to C:\Users\YourUsername\AppData\Local
So in the end you will get something like C:\Users\YourUsername\Appdata\Local\BANDAI NAMCO Entertainment
Hope that helps.
Not Enough Space
If you get *not enough space to save* issue - you can try to fix this either by freeing some space on a drive where your *Users* folder is located (and Windows as well usually), or Right-Click on your game in steam library - Properties - Local Files - Verify Integrity of Game Files. It should work in most cases.
- In case everything above fails to solve the issue ( which happens rarely ), you also may try uninstalling the game, then reinstalling it to another drive.
Source: https://gameplay.tips/guides/7253-one-piece-pirate-warriors-4.html