This is the "engine" that allows the mod to run.
The primary requirement is the installer for version 1.12.2. Forge acts as the "hooks" that allow external files to modify the game's engine. file name fapcraftmodv11forge1122jar install
Forge version mismatch. Fix: Reinstall Forge 1.12.2 exactly (not 1.12.1 or 1.12). Cause 2: Java version too new. Fix: Switch your launcher’s Java runtime to Java 8. In the launcher, go Installations > your Forge profile > More Options > Java Executable → browse to javaw.exe from Java 8. This is the "engine" that allows the mod to run