Hey I got the same problem. Turned out that because I unzip the Downgrade Patcher zip file by using rar instead of 7z, because the file was zipped by 7z. You need to unzip it with 7z. After that the game will working fine. Here are the steps:
- Copy the live game to a new folder (name it something like SPT, or name without space), in this case I called it folder A
- Extract everything inside the AKI 1.5.1 to folder A
- Extract the Downgrad Patcher to folder A (USING 7Z)
- Run patcher
- Run server
- Run launcher
- Start the game.
