How do I fix FSX: Steam Edition startup crashes?

FSX: Steam Edition usually crashes on startup because fsx.cfg, the saved default flight, the scenery catalogue or an automatically loaded add-on is invalid. Verify the Steam files, rebuild the active FSX profile, then test without startup modules. The crash stage and Windows faulting module name tell you which component to isolate.

What causes FSX: Steam Edition to crash on startup?

Most FSX startup crashes come from user configuration or add-ons rather than a damaged fsx.exe. Steam file verification repairs stock files, but it does not reset the files stored under AppData, Documents or ProgramData.

Mixed boxed-FSX and Steam Edition installations need extra care. The active profile may be named FSX or FSX-SE, and copying an old boxed configuration wholesale can leave add-ons pointing at the wrong installation.

What does the Windows faulting module name mean?

The faulting module name is the best available clue, but it must be interpreted alongside its file path and the point at which FSX failed.

1. Open Reliability Monitor. Search Windows for reliability, open the reliability history, select the FSX failure and view its technical details.
2. Record the module and path. Note the faulting application, faulting module name, module path and exception code before changing anything.
3. Check Event Viewer if there are no results. Open the Application log under Windows Logs and look for an error matching the exact time that fsx.exe closed.

Never download a replacement for a Windows DLL merely because its name appears in the event. The named system module may only be where Windows recorded damage caused earlier by an add-on.

How do I fix an FSX Steam Edition startup crash?

The safest method is to make one reversible change at a time and launch FSX after each step.

1. Back up the active files. Copy the relevant folder beneath %APPDATA%\Microsoft\, your FSX flight-files folder under Documents and any manually edited files. Do not edit both FSX and FSX-SE blindly; modification dates help identify which profile Steam Edition is using.
2. Verify the Steam files. Open the game’s Steam Properties and use the integrity-verification option under Installed Files. This restores missing or altered stock files, but may also overwrite deliberate edits made directly to stock aircraft or scenery.
3. Rebuild fsx.cfg. Close FSX and rename the active fsx.cfg to fsx.cfg.old. FSX should create a clean configuration on the next launch. Display, realism, sound and controller settings return to defaults, while the old file remains available for reference.
4. Disable automatic startup modules. In the same profile folder, rename dll.xml and exe.xml with an .old suffix. These files load DLL modules and external utilities during startup. If FSX works, restore the files and isolate entries in small groups using our procedure for finding the aircraft, gauge, scenery or startup module causing a crash.
5. Bypass the saved default flight. Temporarily move the FSX saved-flight files out of Documents and rename Logbook.BIN if present. A damaged default flight can reference a missing aircraft, weather file or scenery area. If FSX reaches its main screen but crashes only after selecting Free Flight, follow the checks for aircraft, default-flight and scenery failures during Free Flight loading.
6. Remove obsolete local DLL workarounds. Inspect the FSX installation directory for DLLs you knowingly added, particularly an old local UIAutomationCore.dll, d3d9.dll or other graphics injector. Rename only the user-added copy for testing. Never alter UIAutomationCore.dll in Windows system folders.
7. Test a clean scenery catalogue. Back up the active scenery.cfg beneath the relevant Microsoft folder in %PROGRAMDATA%, rename it and start FSX. If this solves the crash, restore custom scenery gradually and check that every path exists. Disconnected drives and renamed scenery folders are common causes.
8. Remove forced compatibility settings. Test Steam and FSX at the same privilege level, preferably with neither forced to run as administrator. A frequent mistake is elevating fsx.exe while leaving Steam at normal privileges. Also clear old Windows compatibility modes unless a specific add-on requires one.
9. Check security software and prerequisites. Review quarantine or protection history for blocked FSX and add-on files rather than permanently disabling protection. Repair legacy DirectX, SimConnect or runtime components using the installers supplied with FSX or the affected add-on, not a generic DLL bundle.

Is the Windows 10 Startup folder involved?

The Windows 10 Startup folder is not where FSX loads its normal add-on modules. FSX uses dll.xml and exe.xml; placing UIAutomationCore.dll or another FSX DLL in the Windows Startup folder will not fix the simulator.

To inspect utilities launched when you sign in, press Windows+R and enter shell:startup. The all-users folder is available through shell:common startup, while other startup applications appear in Windows Startup Apps or Task Manager. Temporarily disable only utilities plausibly connected with FSX, such as an add-on launcher or graphics overlay.

What if an Aerosoft or other add-on is named in the crash?

An Aerosoft filename in the faulting-module details is evidence against that particular component, not every product from the same publisher.

Disable its dll.xml or exe.xml entry, or temporarily remove the associated aircraft or scenery, then retest with stock content. Confirm that the installed product supports FSX: Steam Edition and repair it with its own installer if necessary. Complex aircraft and utilities may also require a legacy SimConnect component supplied with FSX or the product.

Restore add-ons by category and then by halves until the crash returns. For scenery, restore required libraries before airports that depend on them; otherwise a missing library can make a working airport appear faulty.

What if Steam itself crashes on startup?

If steam.exe closes, freezes or fails before fsx.exe starts, resetting FSX configuration files will not repair the Steam client.

Restart Windows, remove forced compatibility settings, check security-software history and ensure Steam and FSX are not running at mismatched privilege levels. If Steam stays open but reports an initialisation failure when FSX launches, use our Steam-client initialisation and permissions checks for FSX on Windows 11. The same distinction matters on Windows 10: identify whether the failed process is steam.exe or fsx.exe.

What if the fixes did not help or there are no crash results?

If the first fixes did not help, establish whether FSX is crashing, hanging or never being launched by Steam.

• Crash: fsx.exe disappears and Windows records an application failure. Continue isolating the faulting module, scenery and user profile.
• Hang: fsx.exe remains in Task Manager and shows Not responding. A missing scenery path or slow startup module is more likely; use our diagnosis for splash-screen hangs and unusually slow FSX startup.
• No launch: no fsx.exe process appears. Concentrate on Steam initialisation, permissions, security software and installation prerequisites.

Repeat the test with a clean fsx.cfg, no dll.xml or exe.xml, no user-added DLLs in the FSX directory, a stock flight and a clean scenery catalogue. That baseline is far more useful than repeatedly reinstalling over the same faulty profile.

Should I reinstall FSX: Steam Edition?

Reinstall FSX only after a verified stock installation still crashes with a clean profile, no startup modules, default scenery and no local DLL workarounds.

A normal Steam uninstall can leave AppData configuration, ProgramData scenery settings and third-party files behind, so reinstalling alone often changes nothing. Back up your files, remove affected add-ons with their own uninstallers, rename the leftover FSX profile and installation folders, then reinstall and launch the stock simulator once before restoring content. Add aircraft, gauges, utilities and scenery in separate groups so the fault is immediately identifiable if it returns.