Encountering a red border around your screen while playing League of Legends can be a frustrating distraction. This border can occur for a few different reasons, with the most common being related to in-game settings designed for multi-monitor setups. However, other system or software issues can also be the culprit. This guide will walk you through the potential causes and provide solutions to get back to a seamless gaming experience.
The Most Common Cause: Mouse Screen Lock
The most frequent reason for the red border is the “Mouse Screen Lock” feature within League of Legends. This feature is intended to confine your mouse cursor to the game window, which is particularly useful for players with multiple monitors to prevent accidentally clicking outside the game during intense moments. It is typically toggled on and off using the F9 key.

How to Remove the Red Border (Mouse Screen Lock):
- Press F9 Again: The simplest solution is to press the F9 key once more. This should toggle the Mouse Screen Lock feature off and immediately remove the red border, allowing your mouse to move freely across your screen.
- Check and Rebind Key Binding: If pressing F9 doesn’t work, the hotkey for this feature may have been changed.
- Open the Settings menu in League of Legends (usually by pressing Esc in-game or clicking the cogwheel in the client).
- Navigate to Hotkeys.
- Expand the Additional Hotkeys section.
- Expand the Menus section.
- Find the Toggle Mouse Screen Lock option.
- Check which key it is bound to and press that key. You can also rebind it back to F9 or a different key to prevent accidental activation in the future.

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Other Potential Causes and Solutions:
While the Mouse Screen Lock is the most common cause, a red border can sometimes indicate other issues:
- Resolution Mismatch: If your in-game resolution doesn’t match your monitor’s native resolution, it can sometimes cause display anomalies like a red border.
- Go to Settings > Video.
- Ensure your Resolution setting matches your monitor’s native resolution.
- Try switching between Windowed, Borderless, and Fullscreen modes to see if it resolves the issue.
- Graphics Driver Issues: Outdated or corrupted graphics drivers can lead to various graphical glitches.
- Ensure your graphics drivers are up to date. You can download the latest drivers from the website of your graphics card manufacturer3 (NVIDIA, AMD, or Intel).
- Consider performing a clean installation of your graphics drivers if simply updating doesn’t help.
- Third-Party Software Interference: Certain third-party applications with overlays or recording features can sometimes conflict with League of Legends and cause visual issues like a red border.
- Temporarily disable any overlay software (e.g., Discord overlay, GeForce Experience overlay, overwolf) or screen recording programs that are running in the background while you play.
- If you identify a specific program causing the issue, check its settings for game compatibility or overlay options.
- Windows Accessibility or Game Features: In some cases, Windows features like Focus Assist, Xbox Game Bar, or Ease of Access settings (specifically visual notifications that highlight active windows) can cause a red border to appear.
- Disable Focus Assist: Go to Windows Settings > System > Focus Assist and turn it off or adjust its rules.
- Disable Xbox Game Bar: Go to Windows Settings > Gaming > Xbox Game Bar and toggle it off.
- Check Ease of Access Settings: In Windows Settings, search for “Ease of Access” or “Accessibility” and look for visual settings that might be adding borders or highlights to windows.
Additional Tips:
- Some users have reported that pressing other function keys in the F6-F10 range has occasionally helped resolve a red border issue, although F9 is the primary key for Mouse Screen Lock.
- If the issue persists after trying the steps above, restarting your computer and the League of Legends client can sometimes resolve temporary glitches.
- Ensure your League of Legends client and game are fully updated.
By systematically checking these potential causes and applying the corresponding solutions, you should be able to remove the red border and enjoy playing League of Legends without visual disruption.
Written by:
Christian