Here's tutorial how to open Game without errors:
Step 1: Install AMD driver 23.10.01.14 version:
https://drivers.amd.com/drivers/amd-software-adrenalin-edition-23.10.01.14-win10-win11-work-graphs.exe or
https://www.amd.com/en/resources/support-articles/release-notes/RN-RAD-MS-AGILITY-SDK-2023-6-711.html
Step 2: Download d3d12.dll (by @edwardbenchmarks):
https://drive.google.com/file/d/1xJ4HcJmYz19D8McBys-yKuwBdiidVtO1/view?usp=sharing and put file in steamapps/Forza Horizon 6 folder (where the Game's forzahorizon6.exe is stored)
Step 3: Open game/Launch Game, you will get message warning, Click ıgnore warning.
Step 4: After error fhe01 code, GO to "C:\Users\%username%\AppData\Local\Temp\" and delete folder "fortetemp. Scratch" or rename to "fortetemp. Scratchbi4"
Step 5: Open again Game, Click ignore warrning and will let you in Game without errors.
Step 5.1: If you still have message error fhe01, keep deleting folder fortetemp. Scratch until the error disappears (follow step 4)
Or.
Step 5.2: If you still have message error fhe01, keep launching Game until the error disappears.
Fix FH205 error, you need to download AMD driver 23.10.01.14. (follow step 1)enjoy.