Locate files named UnityCrashHandler.exe or UnityCrashHandler64.exe .

Here is a comprehensive guide to understanding and fixing this common controller issue. Understanding the Error

The application may fail if it cannot verify its state due to a firewall blocking its outbound connection. Step-by-Step Fixes for Error Code 4 1. Configure Windows Firewall (The Most Effective Fix)

In some cases, specific game files like the Unity Crash Handler trigger this error during startup.

If you’ve encountered the while using x360ce in 2021 or later, you're not alone. This error typically occurs when the application’s built-in security or verification routine is blocked or corrupted, preventing the emulator from launching or communicating with your game.

Choose and browse to the executable (EXE) of the game or software causing the error. Select Block the connection .

If you are playing a game built on the Unity engine, this file is a known culprit for "Self protection failed" errors. Navigate to your game's installation directory.