How do I reinstall FS2004 without losing add-ons?

To reinstall FS2004 without losing add-ons, back up the entire Flight Simulator 9 folder, the FS9 configuration folder, saved flights and flight plans, plus every add-on installer and licence key. Reinstall FS2004 cleanly, apply the FS9.1 update, then restore add-ons in small, tested batches rather than copying the old installation over the new one.

What should I back up before reinstalling FS2004?

Make a verified backup on a different drive before running the uninstaller. The essential locations are not all inside the main FS2004 directory.

• The complete FS2004 installation folder: copy the folder containing fs9.exe. This preserves custom content under Aircraft, Addon Scenery, Gauges, Effects, Modules, Sound and Texture, along with any other modified files.
• The FS9 user configuration folder: back up %APPDATA%\Microsoft\FS9. It contains FS9.cfg, including graphics, sound, control and simulator settings. AppData is hidden by default, but the path can be pasted directly into File Explorer.
• Saved flights and plans: copy the Documents\Flight Simulator Files folder. Its displayed location may be called My Documents on older versions of Windows.
• External scenery: copy any scenery packages stored outside the FS2004 folder. Take screenshots of the Scenery Library so that its activation state and layer order can be rebuilt.
• Installers and licences: retain installers, updates, serial numbers and activation details for complex aircraft, scenery and utilities. If a licensed product provides a deactivation function, use it before removing the old installation.
• Add-on-specific data: check Documents, AppData and ProgramData for presets or databases created by installed products. Copying the FS2004 folder alone will not preserve these.

Open several files from the backup and confirm its size before uninstalling. A second copy on the same disk does not protect against disk failure.

How do I perform a clean FS2004 reinstall?

A clean reinstall keeps the old add-ons isolated until an unmodified copy of Microsoft Flight Simulator 2004 has launched successfully.

1. Close FS2004 and related utilities. Finish and verify all backups before changing the installation.
2. Uninstall FS2004 through Windows. Do not manually delete the original directory first, because the uninstaller may need its files and records.
3. Isolate anything left behind. If the uninstaller leaves the Flight Simulator 9 folder, rename it to something such as FS9.OLD. This prevents third-party files from being mixed automatically into the new installation.
4. Install a fresh copy. Keeping the original path reduces problems with old installers and scenery entries that use absolute paths. If protected Program Files permissions caused the original trouble, use a simple location outside that folder and expect to correct old paths.
5. Launch FS2004 once and then close it. This creates the new user configuration and establishes the installation details that add-on installers expect.
6. Bring the simulator up to FS9.1. Apply the update if the new installation is not already patched, following our safe FS2004 patch and installation order.
7. Test the untouched simulator. Load a default aircraft at a default airport before restoring anything. If it fails here, add-ons are not yet the cause.

Do not restore the old fs9.exe, default DLLs or an entire set of stock folders. That can undo the FS9.1 update or reintroduce the damaged file that prompted the reinstall.

Should I copy or reinstall each add-on?

Copy simple, self-contained freeware, but reinstall products that use activation, shared modules, external programs, fonts, registry entries or files outside the simulator folder.

For a precise map of where aircraft, panels, gauges, effects and modules belong, use our FS2004 add-on folder guide. Scenery requires both the correct folder structure and a library entry; our scenery restoration and activation instructions cover that separate process.

Never paste the entire backed-up installation over the fresh one. Restore one product or a small category at a time, launch FS2004, and load an appropriate test flight after each batch. If the original reinstall was intended to fix crashes or poor performance, leave the newly generated FS9.cfg in place and reapply settings manually.

Why are add-ons missing after the reinstall?

Most missing add-ons are caused by an incomplete dependency, an extra folder level, an inactive scenery entry or an installer that cannot detect the new FS2004 path.

• An aircraft is not listed: check that its folder is directly under Aircraft, not nested inside another folder. A repaint also needs the correct base aircraft and its original configuration entry.
• Gauges are black or absent: restore the aircraft's required gauge files and modules rather than repeatedly copying the panel folder. Some complex panels must be reinstalled.
• Scenery does not appear: confirm that the package contains the expected scenery and texture subfolders, add it to the Scenery Library, and check its layer order. Correct any absolute path that still points to the old location.
• AI traffic is missing: restore the relevant traffic files and AI aircraft, then make sure the simulator's traffic setting is not at zero.
• An installer cannot find FS2004: run the clean simulator once first. If detection still fails, use the documented method to repair FS2004 installation registry information rather than guessing registry values.
• The original crash returns: remove the most recently restored batch and test again. Modules, shared gauges and an old FS9.cfg should be checked before blaming the fresh base installation.