In some cases — especially for players using Windows 11 — problems with launching the game may occur. MuOnline is an old title, and newer versions of Windows can sometimes cause additional issues when trying to connect. Fortunately, the problem that appears on Windows 11 is easy to fix and allows players to get back into the amazing world of MuOnline.
What’s the issue?
Players trying to start the game may see an error message such as “Missing file: main” or “Missing file: main.premium.”
If you’re using Windows 11, follow the simple steps below to fix this issue and continue your adventure without interruption.
Another common issue is that MAIN.exe suddenly disappears from the computer — the game window closes automatically without any warning.
How to RESOLVE INDOWS 11 MuOnline problem?
- Right-click anywhere on your desktop and select “Personalize.”
- Then, from the menu on the left side, choose “System.”
- Scroll down to the bottom of the list in the System section and click on “About.”
- In the “Device specifications” panel, click “Advanced system settings.”
- A new window called “System Properties” will appear. Go to the “Advanced” tab and, under the “Performance” section, click the “Settings…” button.
- Next, open the “Data Execution Prevention” tab and make sure the option “Turn on DEP for all programs and services except those I select:” is enabled.
- The list below should be empty — click the “Add…” button and select the main.exe file from your FORT MU game client (the folder where the game is installed).
- Finally, click “Apply,” then “OK” to close all windows.
- Restart your computer. From now on, MuOnline should run smoothly on Windows 11.