Why is Hollow Knight Mod Installer Not Working? Moreover, the problem is likely to appear due to many different reasons, so below find out the common culprits responsible for the problem and follow the fixes given one by one to solve the problem and start suing the Hollow Knight Mod Installer. The mod installer not working in the Hollow Knight problem is likely to appear when the installer is not compatible with the game version so make sure to download the compatible and stable version of the mods installer from the trusted site.