FSX keeps crashing? Diagnose Windows 11, Steam Edition, add-on, configuration, scenery and out-of-memory faults with fixes that isolate the cause.
FSX and FSX: Steam Edition usually keep crashing because an add-on, corrupt configuration, bad saved flight, scenery conflict, incompatible gauge, graphics hook or the simulator’s 32-bit memory limit is being triggered. Match the crash to its timing, run a stock test, inspect Windows’ fault report, then isolate one component at a time.
Is “FSX 2020” the same simulator?
No. FSX means Microsoft Flight Simulator X, while Microsoft Flight Simulator (2020) is a different simulator with different files, settings and crash causes. FSX: Steam Edition belongs to the FSX family; Microsoft Flight Simulator 2020 and 2024 do not.
If the simulator has a modern world-map interface rather than the classic FSX Free Flight menu, use our crash troubleshooting for Microsoft Flight Simulator 2020 and 2024. The AppData paths and FSX repairs below do not apply to those simulators.
Why does Microsoft Flight Simulator X keep crashing?
The point at which FSX crashes is usually the strongest clue to its cause.
| When FSX crashes | Likely cause | Best first test |
|---|---|---|
| At the splash screen or before the menu | Corrupt configuration, damaged logbook, malformed XML or a startup module | Generate a clean configuration and temporarily disable startup modules |
| When selecting Free Flight or opening the aircraft list | Bad default flight, logbook, aircraft, panel, gauge or menu-related module | Use a clean configuration and select a stock aircraft |
| While loading one saved flight | Saved-flight data, weather, aircraft or scenery used by that flight | Create a new flight instead of loading the save |
| At one airport or geographic position | Conflicting or damaged scenery, mesh, landclass or terrain data | Deactivate add-on scenery covering that area |
| When opening a panel or changing view | Incompatible gauge, panel or aircraft model | Repeat the action in an unmodified stock aircraft |
| Late in a flight or near a detailed airport | 32-bit address-space exhaustion | Reduce aircraft, scenery, texture, weather and traffic demand |
| Only with DX10 Preview, an overlay or injector | Rendering hook or graphics-driver conflict | Disable that feature and repeat the identical flight |
| Only when exiting FSX | An external module or programme failing during shutdown | Disable modules and close external tools before starting FSX |
How do I find the exact cause of an FSX crash?
Windows Reliability Monitor can identify the module involved and distinguish a repeatable add-on failure from a vague application crash.
- Reproduce the crash once. Record the aircraft, airport, weather, view, elapsed flight time and exact action that triggered it.
- Open Reliability Monitor. Search Windows for
View reliability history, select the FSX failure and open its technical details. - Read the module name and path. A third-party DLL inside an add-on, gauge or module folder is a strong lead. A graphics or overlay DLL points towards the rendering layer.
- Check whether the trigger repeats. Use the same aircraft, location and action. A one-off crash gives weaker evidence than a failure that occurs at the same point every time.
- Disable one suspect and test again. Do not change the scenery, aircraft, graphics settings and configuration simultaneously; that may hide the crash without identifying its cause.
ntdll.dll and KERNELBASE.dll often show where Windows recorded the failure, not what caused it. An access-violation code is similarly generic. Core FSX modules such as terrain or graphics components can also crash after receiving bad data from scenery, an aircraft or exhausted memory, so do not replace the named system file with a DLL downloaded from the internet.
What is the safest order for fixing an FSX crash?
The safest method is to preserve the existing files, establish a stock baseline and reset only the layer implicated by the crash.
- Back up the user profile. Close FSX, open
%APPDATA%\Microsoftand copy the active FSX profile somewhere safe. It is usually namedFSX; side-by-side boxed and Steam installations may use a Steam-specific profile name. - Run a new stock flight. Choose an unmodified default aircraft, an airport using default scenery, the
Clear Skiesweather theme, no AI traffic and DX10 Preview off. Close external weather, traffic, tracking, recording and overlay programmes. - Interpret the result. If the stock test works, concentrate on the aircraft, scenery, weather or tool used by the failing flight. If it still crashes, continue with the configuration and startup layers.
- Reset the active configuration. Rename the configuration file rather than deleting it, then start FSX so it creates a clean replacement. It is normally
fsx.cfg, although side-by-side installations can use different profile or file names. - Disable startup modules. Back up and temporarily rename
dll.xmlandexe.xmlin the active profile. A missing file is normal. Renaming these files prevents listed modules and external programmes from starting but does not uninstall them. - Repeat the same test. Restore settings and modules individually. Copying the entire old configuration over the new one can immediately restore the fault.
A stock aircraft alone does not create a completely clean simulator. Global mesh, texture replacements, scenery entries and startup modules can remain active everywhere, which is why the configuration and XML tests matter when even a stock flight crashes.
Why does FSX crash when I select Free Flight?
A Free Flight crash usually means FSX is trying to read a corrupt default situation, logbook, selected aircraft or menu-related add-on before the flight itself has loaded.
Start with a clean configuration and do not load an old saved flight. If the crash remains, back up and rename Logbook.BIN in the simulator’s flight-files folder under Documents, then test again. Renaming preserves the old logbook; deleting it first removes the chance of recovering flight history.
If the aircraft-selection screen opens but one aircraft causes the crash, stop selecting it and test a stock model. A malformed aircraft configuration, panel, model or gauge may crash FSX while it builds the preview, before the aircraft reaches the runway.
How do I prove an add-on is making FSX crash?
An add-on is responsible when a repeatable crash disappears with that component disabled and returns when it is restored.
- Aircraft and gauges: use an unmodified stock aircraft. Crashes tied to one panel, instrument, view or aircraft selection usually implicate that aircraft’s panel or gauge files.
- Scenery: deactivate the scenery covering the failing airport or route in the Scenery Library. If several packages overlap, restore them in groups and then individually to find the conflict.
- Weather and traffic: close the programme completely rather than hiding its window. Repeat the flight using built-in weather and no AI traffic.
- Startup modules: test with the backed-up
dll.xmlandexe.xmlrenamed. If FSX starts, restore one entry at a time rather than restoring both files unchanged. - Steam compatibility: check that a legacy installer wrote to the Steam Edition installation and profile rather than an old boxed-FSX path, particularly when both editions have existed on the same computer.
Our step-by-step add-on isolation process covers aircraft, gauges, scenery and external modules without requiring a full FSX reinstall.
Do not mass-delete the Gauges folder or remove every file sharing the faulting module’s name. Add-ons often share libraries and SimConnect components. Use the add-on’s uninstaller where possible, keep backups and remove only the package that failed the controlled test.
Could FSX be running out of memory?
Yes. FSX is a 32-bit application with a limited virtual address space, regardless of how much physical RAM is installed in the computer.
A complex aircraft, detailed airport, high-resolution textures, dense weather, autogen and AI traffic all consume that same address space. Typical clues include an explicit out-of-memory message, missing or black textures before the crash, or a failure late in a flight as a detailed destination loads.
Choose a lighter aircraft or scenery package when only one demanding combination fails. Reduce texture resolution, autogen, scenery complexity, weather detail and AI traffic when several heavy flights fail. Increasing the Windows page file may help general system pressure, but it does not remove FSX’s 32-bit address-space ceiling.
For an explicit memory warning or a consistent late-flight failure, follow our targeted FSX out-of-memory fixes rather than reinstalling the simulator.
How do I stop FSX crashing on Windows 11?
FSX crashing on Windows 11 is usually caused by a legacy add-on, graphics hook, protected-folder write problem or driver conflict rather than one universal Windows 11 fault.
- Start without compatibility overrides. Remove stacked XP or Windows 7 compatibility settings while testing. Apply a compatibility option only when a repeatable fault shows that it is needed.
- Disable rendering hooks. Turn off DX10 Preview, overlays, recording hooks, frame injectors and post-processing tools, then repeat the same flight.
- Check write access. If settings will not save or Windows Security records a blocked action, allow the specific FSX executable or correct the affected folder permissions. Do not disable security protection globally.
- Use official prerequisites. Repair the legacy DirectX and runtime components supplied with FSX, Steam or the relevant add-on. Never replace files in Windows system folders with loose DLL downloads.
- Remove instability while diagnosing. Return CPU, GPU and memory overclocks to standard settings and reinstall the correct graphics driver if clean stock flights continue to fail.
Running FSX permanently as administrator is not a general crash fix. It can mask an installation-permission problem and create mismatched privileges between FSX and external tools. For a future clean installation, a dedicated simulator library outside heavily protected Windows folders can make old add-on installers easier to manage, but do not drag an existing FSX folder to a new location because its registered paths will no longer match.
A blue screen, complete system restart or graphics-driver reset is not a normal FSX application crash. That points towards a driver, overclock, temperature, power or hardware problem and should be investigated at the Windows level before changing aircraft or scenery.
What if the first FSX fix did not help?
If a clean configuration and stock test still crash, repair the installation layer and keep the old profile isolated until FSX has completed a successful stock flight.
- Verify FSX: Steam Edition files. Back up altered default files first because verification can replace them. Verification does not remove every extra third-party file and does not normally reset the per-user AppData profile, so a successful check does not prove that add-ons are innocent. Our Steam Edition startup-crash procedure explains the correct verification and clean-profile sequence.
- Repair a boxed FSX installation. Use the original installer’s repair option, then restore the service-pack or Acceleration state appropriate to that installation before testing third-party content.
- Test from a separate Windows user profile. If FSX works there, the fault is in the original user’s AppData, Documents files or permissions rather than the main installation.
- Reinstall only as the final software test. Rename leftover FSX AppData and Documents folders before the first launch, then test a stock flight before restoring any add-on. An uninstall that leaves the damaged profile in place can reproduce the same crash immediately.
If the simulator now works, restore one aircraft, scenery area or module at a time. If it still crashes in every stock scenario with a fresh user profile, repaired files, no external modules and standard hardware settings, the remaining evidence points towards the graphics driver, Windows components or system stability rather than FSX content.