How do I update FlightGear safely?

To update FlightGear safely, back up your user profile and add-ons, obtain a trusted installer, and keep custom scenery and aircraft outside the simulator’s supplied data folder. Test the new release with a clean profile before restoring add-ons in small groups. Never merge an old FG_ROOT into the new installation.

What should I back up before updating FlightGear?

Back up FlightGear’s writable user profile, every custom-content folder and any launch options that define non-standard paths. The actual locations vary by operating system and installation method, so the distinction between the following areas matters more than their exact folder names.

Also record custom launcher arguments, scenery search order, additional aircraft directories and controller assignments. If you previously placed add-ons inside the installation directory, copy only those custom files into a holding folder; do not preserve the complete old data tree.

Scenery is much easier to protect when it lives outside FG_ROOT. Our instructions for organising FlightGear scenery in separate user folders explain the safer arrangement.

Safest FlightGear update procedure

Treat a full FlightGear release as a fresh application installation rather than copying new files over old ones.

1. Identify the installation method. Note whether FlightGear came from a downloaded installer, a Linux package manager, Flatpak or a source build. Update through the same channel to avoid duplicate executables and conflicting profiles.
2. Check compatibility. Before a major upgrade, compare the computer with the FlightGear operating-system, graphics and hardware requirements. Older graphics drivers are a common cause of problems that appear to be failed updates.
3. Close FlightGear completely. Then back up FG_HOME, custom content and path settings. Do not make the backup while the simulator is writing preferences or scenery data.
4. Obtain a clean package. Use the trusted FlightGear installer packages and installation guidance rather than an unknown repack.
5. Preserve a rollback route. Install beside the previous release where the platform and installer permit it. If the update must replace the old application, retain the old installer or package details as well as your user-data backup.
6. Create a clean profile. Rename the existing FG_HOME folder temporarily instead of deleting it. Launching FlightGear should create fresh user data, which separates update faults from stale settings.
7. Test only supplied content. Load a bundled aircraft at a default airport and check the cockpit, controls, sound, terrain and frame rate. Do this before enabling custom aircraft, scenery or navigation data.
8. Reconnect add-ons gradually. Add custom aircraft and scenery through the launcher’s additional-content paths, one category at a time. Restart and test after each group so a failure has an obvious cause.
9. Remove the old release later. Keep it until the updated simulator has completed several normal flights and all essential controls and add-ons work.

On Windows and macOS, use a separate installation destination or application copy where the package supports it. On Linux, update through the same package manager or Flatpak installation used originally; a distribution repository may intentionally offer a different release from a manually downloaded build. Source builds need a clean build directory and the matching FlightGear data revision.

Should I uninstall the old FlightGear version first?

No—retaining the old release is safer until the update has passed its basic tests. Some installers perform an in-place upgrade, but manually dropping a new executable into an old installation is not an acceptable substitute.

Each executable must use the matching FG_ROOT. A stale shortcut, launcher option or --fg-root override can start the new executable against old data, producing missing menus, aircraft errors or an immediate exit. Check both the displayed version and the executable path after updating.

To roll back, close the updated release, restore or reconnect the old user profile, and start the old executable with its original data folder. Never point the old executable at the new release’s FG_ROOT.

Will aircraft, scenery and navigation data still work?

Separately stored scenery often remains usable, while third-party aircraft and user-supplied navigation data need more careful testing.

• Bundled aircraft: Use the copies supplied with the updated simulator. Copying older bundled aircraft over them can replace corrected scripts and systems with incompatible files.
• Downloaded aircraft: Restore each aircraft separately. If one causes errors, remove it and obtain a build intended for the newer FlightGear release rather than modifying core simulator files.
• Custom scenery: Re-add its search path and check the path order. An old package placed ahead of newer scenery can override airports, terrain or objects even though the update itself is sound.
• Navigation data: Test the database supplied with FlightGear before restoring a user override. Navigation data has its own update process; use our safe procedure for installing FlightGear navigation data if frequencies, procedures or waypoints need refreshing.
• Controller settings: A clean profile will not contain every previous assignment. Recreate essential axes and buttons first, then import old settings selectively if required.

Why does FlightGear fail after an update?

Most post-update failures come from mixed data versions, stale profile files or an incompatible add-on rather than the new executable itself.

If the clean profile and supplied content work, the installation is fundamentally sound. Restore add-ons individually—or in halves when diagnosing a large collection—until the item that triggers the fault is identified.