Why does FSX say it is already running when it is closed?

Microsoft Flight Simulator X (FSX), including FSX: Steam Edition, shows “already running” when the previous fsx.exe process has not fully closed, even though its window has disappeared. End that process in Windows Task Manager, then relaunch FSX. If it keeps happening, an add-on module, configuration fault or background utility is blocking shutdown.

How do I clear the FSX “already running” error?

Clear the message by dealing with the existing process; reinstalling FSX is not the first fix.

1. Open Task Manager. Press Ctrl+Shift+Esc, select More details if shown, and open the Processes or Details tab.
2. Find the FSX process. Look for fsx.exe; older Windows versions may display it as fsx.exe *32. If you have only just launched FSX and the process is active, allow it time to load rather than clicking the shortcut again.
3. End a process that is genuinely stuck. Select fsx.exe and choose End task. Any unsaved flight progress will be lost. If access is denied, reopen Task Manager as an administrator.
4. Reset Steam's status if necessary. With FSX: Steam Edition, if fsx.exe has gone but Steam still labels the simulator as running, close associated add-on utilities, exit Steam fully and reopen it.
5. Restart Windows if no process is visible. A restart clears hidden sessions and remaining single-instance state. Do not end unrelated Windows services or the Steam Client Service.

Rapidly clicking the FSX shortcut twice is a common cause. With numerous add-ons installed, the first instance may be loading in the background before any simulator window appears.

Why does FSX stay running after I close it?

The main FSX window can disappear before every module inside fsx.exe has finished releasing files, devices and network connections.

• In-process add-ons: aircraft gauges and weather, traffic, camera or network modules can hang during shutdown. Components loaded through dll.xml are frequent suspects.
• External utilities: programmes started through exe.xml may fail to disconnect cleanly or may cause Steam to retain its Running status.
• A hidden error dialogue: FSX or Windows Error Reporting may be waiting behind another window after a shutdown crash.
• A damaged configuration or saved situation: FSX may freeze during startup with no visible window, so the next launch attempt finds the first process.
• Another Windows session: an FSX process owned by another signed-in user can remain active.

The warning is normally a shutdown or startup symptom, not an activation failure and not proof that a second visible copy of FSX is open.

How do I find what prevents FSX shutting down?

The quickest diagnosis is to prove that a clean, default flight exits normally, then add your usual components back one at a time.

1. Protect your files first. Follow our steps to back up the active FSX profile, saved flights and add-on settings before resetting anything.
2. Run a controlled test. Close weather engines, traffic tools, camera utilities and other companion programmes. Start FSX with a default aircraft and an ordinary default airport, then exit from the simulator menu.
3. Disable recent additions first. If the clean test works, re-enable external utilities and add-on modules individually. Use the add-on's own disable option where available; otherwise back up and temporarily rename the relevant dll.xml or exe.xml file in the active FSX application-data profile.
4. Test a fresh configuration. With FSX closed, rename FSX.cfg to FSX.cfg.old. FSX will create a new configuration file on its next launch. The active profile folder may be named differently for boxed FSX and Steam Edition, especially when both have existed on the same computer.
5. Check the recorded fault. If FSX crashes rather than merely hanging, Windows Reliability Monitor may identify a faulting gauge or DLL. Our FSX crash diagnosis and repair steps cover configuration resets and module isolation in more depth.

A mistake we see constantly is removing several add-ons and resetting every configuration file at once. That may hide the problem, but it does not tell you which component caused it. Change one variable, launch FSX and test shutdown after each change.

If the fault survives a fresh profile with third-party modules disabled, use Steam's file-verification function or the boxed installer's repair option. Back up modified stock aircraft and files first because a repair may replace them.

What if fsx.exe is not in Task Manager?

If fsx.exe is absent, check other Windows sessions and distinguish an FSX message from Steam's running status.

If the sequence is launch, freeze or disappear, then “already running” on the second attempt, investigate the first launch failure. A corrupt Logbook.BIN can cause that pattern, although it is not the usual cause of the message itself. Rather than deleting your flight history immediately, use the utility for repairing damaged FSX logbook entries.