Windows Credential Manager glitches can block the game from authenticating your high-completion save profile.
Note: You may need to rename the new file to match the naming convention of your original file, depending on whether you are using Steam or Microsoft Store.
How to Fix Forza Horizon 5 100% Save Game Errors and Recover Your Progress forza horizon 5 100 save game fix
Forza support has identified a potential oversight in the save mechanics: when you reach a certain number of save objects (tunes, cars, liveries, photos), the game may struggle to save correctly. Deleting some objects—particularly unused liveries and tunes—can give you some "headroom" for your save file to function properly.
One of the most reliable methods to bypass a corrupted save is to force the game to create a completely fresh local save: Windows Credential Manager glitches can block the game
If you're switching platforms or have a working save on one version but not the other, advanced users have found ways to convert saves between Steam and Microsoft Store versions. This process requires specialized tools and is not recommended for average users, but dedicated players can find guides on the Forza Mods Discord community.
For console players:
How to Fix Forza Horizon 5 100% Save Game Loading and Sync Issues
Here’s a concise support-style report on the and how to fix common problems related to loading, corruption, or recognition of a completed save file. For console players: How to Fix Forza Horizon