Troubleshooting

Common client issues and how to fix them. Select a topic below to expand it.

Antivirus blocking the game?

  • Disable your antivirus before downloading the game client
  • Add the entire KO folder to antivirus exclusions
  • KO-MyKO Game Folder (e.g., C:/Games/KO-MyKO)
  • KnightOnline.exe
  • Engine.acs
  • Launcher.exe
  • Disable antivirus
  • Re-extract the client from a fresh installation
  • Ensure KnightOnline.exe is not blocked
  • Restart the game
  • Move the client to C:/Games/KO-MyKO
  • Make sure the folder is not syncing with OneDrive
  • Restart the game
  • Press F10
  • Find Font Size
  • Set all values to 9 or 10
  • Toggle BOLD if needed
  • Save settings

Why?

  • Smaller fonts reduce UI rendering load
  • Large fonts cause FPS drops & lag

Low FPS or stuttering on Windows 11?

DXVK (Vulkan) rendering is now built directly into the launcher — no separate download needed.

  1. Open the KO-MyKO Launcher
  2. Find the DXVK toggle
  3. Turn DXVK ON to enable the FPS boost
  4. Turn DXVK OFF to disable it and revert to default rendering

On Windows 11, a feature called Core Isolation → Memory Integrity uses virtualization-based security (VBS).

While this improves security, it can cause significant FPS loss, especially in:

  • Older game engines
  • DX9-based games
  • Applications using low-level hooks (anti-cheats, custom EXE files, overlays)

How to Gain More FPS:

  1. Open Windows Security
  2. Go to Device Security → Core Isolation
  3. Set Memory Integrity → OFF
  4. Restart your PC

Visual guide: How to disable Memory Integrity in Windows Defender

Note: If you know what you install, this is not dangerous for gaming PCs. Many gamers disable this feature on Windows 11 to increase FPS and reduce stuttering.

Pressing Start does nothing and KnightOnline.exe never opens?

Windows Smart App Control may be blocking the game. Disable it, then try again:

  1. Open Settings → Privacy & security → Windows Security
  2. Go to App & browser control → Smart App Control
  3. Select Turn Off
  4. Restart your computer — this change only takes effect after a full reboot, not just relaunching the game
  5. Open the launcher again and try starting the game