How to fix “a critical error has occurred” problem in LoL

The LoL “a a critical error has occurred” problem can seem daunting at first when players are surprised by it, but luckily it’s easy for most player to fix it. We’ll detail exactly how.

Players encountering this error should be seeing a popup that says “a critical error has occurred, process terminated” that stops them from launching or running the League of Legends client. It can be a disheartening error since it often offers no further explanation at all as to what exactly is causing the bug. Luckily, its cause can be narrowed down to one of just a few factors. Here’s how to find the root of the issue and how to fix it.

What causes “a critical error has occurred”?

The timing of this error can vary, some fans get it as soon as they attempt to log on, while others report it popping up regularly during games of League of Legends. Unlike some other errors, it doesn’t give a clear explanation of what’s wrong. This error should cause both client and game to crash, accompanied by the error message. This is often caused by programs like Porofessor and other third-party applications that allow in-game overlays, here’s how to fix this annoying bug.

How to fix “a critical error has occurred” in League of Legends

1. Use your OS Task Manager program and end all programs that feature in-game overlays (Discord and Steam are the most common by far, but other League of Legends-specific apps may be involved, such as Porofessor).
2. Go to the League of Legends folder (default path C:Riot Games\League of Legends) and delete both the Config and Logs folders, allowing them to regenerate cleanly.

If this doesn’t work, there’s a secondary set of steps that affected players can attempt to take.

1. Navigate to the League of Legends folder, and then open the Games folder.
2. Right-click on the League of Legends executable file, click Properties, and finalyly click Compatibilities.
3. Choose the option to “Run this program as administrator” and then select “Disable fullscreen optimization” option as well.
4. Click to apply these changes, then repeat the same process for the LeagueClient.exe file, ensuring that it will be run with administrator privileges and with fullscreen optimization disabled.

These two sets of steps should fix the “a critical error has occurred” issue in LoL. If these steps don’t resolve your problem, you can try uninstalling and then reinstalling the League of Legends client entirely. If that final step doesn’t work, it’s best to file a ticket with Riot Games Support so that they can try to solve the issue themselves.