Fix TerraSync not working in FlightGear by checking download settings, cache paths, permissions, firewall access and damaged scenery tiles.
To fix TerraSync not working in FlightGear, enable automatic scenery downloads, choose a writable cache folder with free space, confirm that folder is in the scenery search path, and allow FlightGear through your firewall. Test again, then check the log for network, permission or failed tile-download messages.
Fix TerraSync in FlightGear step by step
Most TerraSync failures come from a disabled download option, an unwritable cache or FlightGear loading scenery from the wrong location.
- Enable TerraSync: In the FlightGear launcher, find the scenery settings and enable automatic scenery downloading. Command-line users can enable it with
--enable-terrasync. - Choose a separate cache folder: Put the TerraSync cache in a local, writable directory rather than inside FlightGear's installation folder, a protected system directory or a removable drive. Avoid combining downloaded tiles with manually installed scenery.
- Check permissions and storage: Confirm that your user account can create, modify and delete files in the cache. Make sure the drive has free space and that security software is not blocking FlightGear from writing there.
- Verify the scenery search path: FlightGear must search the TerraSync root—the folder containing scenery subfolders such as
TerrainandObjects—rather than one of those subfolders. Custom command-line scenery settings can accidentally omit the cache. Our guide to FlightGear scenery folders and search paths explains how the directory structure should be arranged. - Check network access: Allow FlightGear outbound access through the firewall. Temporarily test without a VPN, proxy or network-level filter if one is in use, but do not leave security protection disabled. An incorrect system clock can also cause secure connection failures.
- Run a controlled test: Start at a location outside your previously cached area and leave FlightGear running long enough to request the surrounding tiles. Large or detailed areas take longer than a single small tile.
- Restart after downloading: If the files arrive after FlightGear has already loaded the area, close and reopen the simulator at the same location. A restart is the most reliable way to make it read newly downloaded terrain and objects.
A normal FlightGear installation includes TerraSync; it is not a separate scenery plug-in. Reinstall only if the launcher lacks its scenery-download controls or the installation itself is incomplete. Our standard FlightGear download and TerraSync overview covers the included on-demand scenery system.
How do I know whether TerraSync is downloading?
TerraSync is working if files are being added to its cache and its status or log shows completed tile requests rather than repeated errors.
- Check whether the cache size and file modification times change while FlightGear is running.
- Search the FlightGear log or launcher output for terms such as
TerraSync,download,HTTP,permissionorscenery. - If the cache remains empty, recheck the enable setting, cache path and network access.
- If folders appear but no scenery files remain after closing the simulator, the location is probably unwritable or being cleaned by security or synchronisation software.
| Symptom | Likely cause | Best next check |
|---|---|---|
| No files appear | TerraSync disabled or blocked | Enable downloads and check firewall access |
| Permission errors | Protected or read-only cache | Select a new user-writable folder |
| Files download repeatedly | Cache changes are not being saved | Check permissions, storage and security software |
| Tiles download but scenery stays generic | Wrong search path or stale loaded tile | Correct the path and restart FlightGear |
| Only one region fails | Damaged local tile or temporary server issue | Test another region, then use a fresh cache |
Why does TerraSync download scenery but not show it?
Downloaded TerraSync scenery usually fails to appear because FlightGear is searching the wrong folder, another scenery source has priority or the current tile was loaded before its download finished.
Check that the search path points to the TerraSync root. A mistake we see constantly is selecting its Terrain folder directly, which prevents FlightGear from finding the related objects and other scenery components correctly.
Temporarily remove or deprioritise older custom scenery covering the same area. It may take precedence over the newer TerraSync tile. Also remember that TerraSync cannot create detail that does not exist for a location, and some visible features depend on FlightGear's rendering settings.
Should I delete the TerraSync cache?
Do not erase the entire cache as the first fix because FlightGear will have to download every required tile again.
Close FlightGear, rename the existing cache and configure an empty writable folder for a test. If the same location works with the clean cache, the old cache or its metadata was damaged. Keep manually installed scenery outside both folders so it cannot be lost during troubleshooting.
Can I use FlightGear scenery without TerraSync?
Yes—offline scenery is the better choice when the simulator runs without internet access, a managed network blocks TerraSync or repeated connection failures cannot be resolved.
Install offline scenery in its own folder and add that folder to FlightGear's scenery search path. Do not make TerraSync download into the same directory. For broad coverage, our offline HD world scenery package avoids live tile downloads, although it requires substantially more local storage.