Completely reinstall FSX on Windows 10 or 11 with the correct clean-up, edition-specific update order and safe add-on testing.
To completely reinstall FSX on a modern PC, uninstall the simulator, remove its leftover installation and user-configuration folders, reboot, then reinstall the correct edition and updates in order. Test a default aircraft before restoring add-ons. FSX: Steam Edition and boxed FSX require different removal and update steps.
What should you save before removing FSX?
Back up only the material you genuinely need: saved flights, screenshots, controller assignments, purchased add-on installers, licence details and any scenery or aircraft you cannot reinstall from their original packages.
A clean reinstall should not immediately inherit the old fsx.cfg, dll.xml, exe.xml or scenery.cfg. One of these files may be the reason for reinstalling. Keep backups for reference, but let FSX create fresh versions.
How do you perform a clean FSX reinstall?
- Identify your edition. Determine whether you have boxed FSX Standard or Deluxe, boxed FSX with Acceleration, or FSX: Steam Edition. Do not mix their installers, service packs or folders.
- Uninstall add-ons first. Remove complex aircraft, weather engines, traffic packages and scenery through their own uninstallers where possible. Their uninstallers may stop working after FSX and its registry path have gone.
- Remove FSX. For boxed FSX, uninstall Acceleration first if Windows lists it separately, followed by Microsoft Flight Simulator X. For Steam Edition, uninstall FSX through Steam and then close Steam.
- Delete the leftovers. Remove or temporarily rename the old FSX installation directory. Common locations include
C:\Program Files (x86)\Microsoft Games\Microsoft Flight Simulator Xfor boxed FSX and the Steam library'ssteamapps\common\FSXfolder for Steam Edition. Steam's uninstall and file-verification tools can leave third-party files behind. - Clear the user profile. Check the Microsoft folders under
%APPDATA%,%LOCALAPPDATA%and%PROGRAMDATA%for folders namedFSXorFSX-SE. Also move or remove the FSX saved-flight folder under Documents. The exact name can differ when boxed and Steam editions have previously coexisted. - Restart Windows. This releases files and completes pending uninstaller changes.
- Reinstall to a clean folder. Run a boxed-disc setup as administrator. When a custom location is available, a short path outside
Program Files (x86), such asC:\FSX, avoids many permission problems. Steam users can choose a suitable Steam library rather than copying an old FSX directory manually. - Apply the correct updates. Follow the edition-specific order below. Never install boxed service packs over Steam Edition.
- Run FSX without add-ons. Let it build a new configuration, load a default aircraft at a default airport, make a short flight and close normally. Only then begin restoring add-ons.
Our full FSX removal procedure covers the remaining folders and installation traces if the normal uninstaller fails or an old installation is still being detected.
Which FSX updates should you install?
| FSX edition | Correct reinstall order | Avoid |
|---|---|---|
| FSX: Steam Edition | Install through Steam, allow its prerequisites to run, then launch FSX | Boxed SP1, SP2 or the Acceleration disc |
| Boxed FSX without Acceleration | Install and activate FSX, launch it once, then install SP1 followed by SP2 | Applying SP2 before SP1 |
| Boxed FSX with Acceleration | Install and activate base FSX, launch it once, then install Acceleration | Applying standalone SP2 after Acceleration |
For a boxed installation without Acceleration, follow the boxed FSX service-pack sequence. Acceleration owners should instead use our modern-PC Acceleration installation steps.
Why did reinstalling FSX not reset anything?
FSX's uninstaller normally removes core simulator files but may leave configuration, scenery-library and add-on data in the Windows user folders. Steam's Verify Integrity function replaces missing or changed core files, but it is not a complete reinstall and does not necessarily remove unknown files added by third-party installers.
If the old menu settings, start-up errors or add-on prompts return immediately, an old profile folder was probably retained or restored. Rename the relevant FSX or FSX-SE folder, start the simulator and check whether a clean profile fixes the fault before deleting the backup.
What if FSX still will not run after reinstalling?
A clean, unmodified FSX installation that fails before the opening screen usually has a Windows prerequisite, permissions, graphics or installation-path problem rather than an aircraft or scenery fault.
- If setup reports that FSX is already installed, repeat the complete removal process rather than using a registry-cleaning utility.
- If a boxed installer cannot write files, run the installer as administrator and avoid installing over an old protected directory.
- If Windows reports a missing DirectX 9-era component, rerun the prerequisite installer supplied with FSX. Having a newer DirectX version does not guarantee that every optional legacy component is installed.
- Do not apply compatibility mode, administrator mode and multiple configuration tweaks all at once. Test one change at a time so the actual fix remains identifiable.
For failures specific to newer versions of Windows, use our Windows 10 and 11 FSX troubleshooting sequence before adding third-party content.
How should you restore FSX add-ons?
Restore add-ons individually, launching FSX after each complex aircraft, scenery region, traffic tool or weather program. Installers should point to the new FSX directory; do not assume they have detected it correctly.
Copying the entire old simulator folder back defeats the clean reinstall and can reintroduce incompatible gauges, duplicate modules and obsolete scenery paths. If the default simulator works and a fault returns after one add-on, leave that package removed until its installer, dependencies and FSX edition compatibility have been checked.