How do I restore or rebuild FS9.cfg in FS2004?

FS2004’s configuration file is named FS9.cfg, not FS2004.cfg. Close the simulator, open %APPDATA%\Microsoft\FS9, rename FS9.cfg to FS9.cfg.old, then start FS2004. It creates a clean replacement automatically. Keep the old file so you can restore it or recover individual settings.

How do I rebuild FS9.cfg safely?

Renaming the existing file is safer than deleting it because the change is completely reversible.

1. Close FS2004: Also close utilities that connect to the simulator, and confirm that fs9.exe is no longer running in Task Manager.
2. Open the configuration folder: Press Windows key+R, enter %APPDATA%\Microsoft\FS9 and press Enter. If that folder is missing, check the account-specific FS9.cfg locations used by different Windows versions.
3. Preserve the original: Turn on file-name extensions in File Explorer, then rename FS9.cfg to FS9.cfg.old. The file may appear simply as FS9 when extensions are hidden.
4. Generate a clean file: Start FS2004 and allow it to reach the main screen or load a default flight. The simulator should create a new FS9.cfg with default settings.
5. Test before changing anything: Check the original fault using a default aircraft and uncomplicated airport. Close FS2004 normally after the test so any changed settings are written to the new file.

If the fault disappears, the old configuration contained a damaged or incompatible setting. Re-enter your preferences gradually rather than immediately copying the entire old file back. Our guidance on reapplying FS9.cfg graphics changes safely explains how to avoid restoring a troublesome tweak.

How do I restore the old FS9.cfg?

Restore the backup only when it was known to work or when the clean configuration made no difference.

1. Exit FS2004 and make sure fs9.exe has stopped.
2. Keep the clean file by renaming the newly generated FS9.cfg to FS9.cfg.clean.
3. Restore the backup by renaming FS9.cfg.old to exactly FS9.cfg, or copy a known-good backup into the folder under that name.
4. Start and test FS2004. If the original problem returns, go back to the clean file rather than continuing to edit the faulty configuration.

Make sure the restored file has not become FS9.cfg.txt and is not marked read-only. Only one file should have the exact name FS9.cfg.

Should I restore the whole file or selected settings?

A complete restore is appropriate for a known-good backup; selective recovery is safer when corruption is suspected.

FS9.cfg is a text file, but FS2004 must be closed before editing it. Preserve section headings and avoid creating duplicate sections. If the syntax or relevant setting is unclear, changing the option inside the simulator is the safer choice.

What does rebuilding FS9.cfg reset?

A fresh FS9.cfg resets many simulator preferences but does not remove installed aircraft, scenery, saved flights or other add-on files.

• Display, rendering and performance options may return to defaults.
• Controller assignments, realism settings, traffic choices and sound preferences may need configuring again.
• Custom FS9.cfg tweaks are removed until manually reapplied.
• Add-ons that wrote their own configuration entries may require their setup utility to be run again.

The scenery library is stored separately in scenery.cfg. Rebuilding FS9.cfg will therefore not cure a damaged scenery library; use the separate scenery.cfg repair procedure for that problem.

Why will FS2004 not create a new FS9.cfg?

If no replacement appears, FS2004 is usually using another Windows profile, lacks permission to write to the profile folder, or is failing before configuration creation finishes.

• Open the folder through %APPDATA% while signed into the same Windows account used to run FS2004.
• Check that the original file was actually renamed and that hidden extensions have not produced a misleading file name.
• Confirm that the FS9 profile folder is writable and that security software has not blocked fs9.exe.
• Do not create an empty FS9.cfg manually; let the simulator build valid default content.
• If FS2004 still crashes with the old configuration removed, investigate the selected flight, aircraft, scenery and loaded modules using our broader modern-Windows startup troubleshooting sequence.

When the same fault occurs with both the old and newly generated configurations, FS9.cfg is unlikely to be the cause. Keep whichever file contains your preferred settings and continue troubleshooting the component that fails during startup or flight loading.