Synctrain support

Frequently asked questions

What is the privacy policy for Synctrain?

See Synctrain privacy policy.

Where can I ask questions that are not answered here?

Please ask your question at the Discussions page.

What kind of support can I expect?

Synctrain is a free app, created by volunteers who are developing it in their free time. While we do care deeply about the app and want it to work well, you are not entitled to any assistance, especially if your situation is highly specific.

Synctrain is based on Syncthing, but the app is not developed by the Syncthing core developers, or endorsed, nor supported by them. If you have an issue with Synctrain, ask any questions to the Synctrain developers only. If necessary we will seek collaboration with the Syncthing core developers to sort out any issues.

Furthermore, Synctrain and Syncthing put you in full control of your data. As we do not have any access to your files, we can not help you in case files get lost.

Synctrain does not start after upgrading to the 2.0 version.

Version 2.0 of Synctrain is based on Syncthing 2.0. This new version uses a different database format for storing information about the state of the files in synchronized folders. When you first open the 2.0 app, it will migrate the old database to the new version. In some circumstances, this may fail. How to resolve this situation depends on the error message shown by the app. Please attempt the following steps:

  1. Force close the app (go into the task switcher and swipe the app away on iOS, or press Cmd-Q on macOS).
  2. Connect your device to a charger, disable low battery mode.
  3. Verify that there is a substantial amount of free disk space (few gigabytes at least) and if not, clean out some files. Then re-open the app (migration will be re-attempted automatically).
  4. Restart the device and try again (restarting sometimes removes some stale files from your device automatically)
  5. Leave the migration process running as long as it takes (do not interrupt it). On iOS devices, the screen should stay on automatically during this process, and when it is finished, it will be allowed to dim again.

If this procedure does not resolve the issue, it may be required to purge the local database. This should not cause any of your files to be deleted, but nevertheless make sure you have a current back-up of your files.

  1. Force close the app again.
  2. Back-up the files that are under synchronization by Synctrain.
  3. Go to Settings -> Apps -> Synctrain -> Troubleshooting and select the options to remove both the v1 and v2 database.
  4. Re-open the app. It should start instantly (no migration required), but will only work properly again after it has exchanged file information with all other peers and has scanned all folders again.

On macOS, the database can be purged manually using the Finder:

  1. Force close the app (Cmd-Q)
  2. Go to the finder, press Cmd-Shift-G (or Go -> Go to folder) and navigate to the following path: ~/Library/Containers/74FE6EE6-9757-48A9-9855-97114F3E66C0/Data/Library/Application Support (note, the long string with numbers and capitals may be different on your machine – navigate to the Containers folder to find the appropriate folder manually if this path does not work)
  3. Remove the index-v1 and index-v2 folders.
  4. Restart the app.

Another option to consider is to fully remove the app and the reinstalling it again. This likely will cause your device to obtain a new device ID. Back up your configuration before doing this.

If these steps do not resolve the issue, it is time to get in touch with us. First, do the following:

  1. Force close the app again.
  2. Go to Settings -> Apps -> Synctrain -> Troubleshooting and enable Debug logging.
  3. Re-open the app – this should lead to a failed migration again.
  4. Force close the app again.
  5. Go to the Files app, to the Synctrain folder, and copy the appropriate (most recent) log file.
  6. Create a post on our Github Discussions page showing (at least) exactly the error message you are seeing. Either upload the log file (after anonymizing it) to Github Discussions, or send it by e-mail.
  7. We will investigate whether the issue can be related to a problem in the app and possibly fix it, if so.

How can I report issues or ideas about the app?

If you are using aTestFlight pre-release version of the app, you can make a screenshot while inside the app. iOS will then provide you a screen where you can submit feedback. This is the preferred way to submit feedback as it comes with some data telling us exactly which version of the app and type of device you are using.

If you are not a TestFlight tester, you may raise your issue or idea on our Discussions page on GitHub or this thread on the Syncthing forum. Please do not use the Syncthing forum to ask for support on the iOS app specifically. The forum is a good place however to discuss things that may be broader than just the iOS app. Alternatively, feel free to contact me directly by e-mail.

In all cases, please ensure that you clearly describe your idea or issue you are experiencing, including any steps I should take to reproduce it. Also include the exact version number of the app you are using, the type of device you are using, and the iOS version. To the extent possible please also describe your configuration (i.e. folders you are synchronizing and in which mode).

Is there a roadmap for the app?

We are tracking issues and feature requests for the app in a private tracker. Prioritization of bug fixes and features is at our full discretion. Follow the developments in the GitHub repository or in our forum thread over at the Syncthing forum for more information. If you are a developer and want to discuss collaboration, feel free to get in touch!

What is the minimum supported version of iOS?

Currently, the most recent version of iOS 17 is required.

The minimum version will be raised either when the maintenance burden of keeping compatibility with older version becomes too large, and/or when we want to add features that can only be added when raising the minimum supported version.

Is there also a version for macOS?

A native version of Synctrain for macOS is available in the Mac App Store for free.

In what regions is Synctrain available?

As of december 2024, both the iOS and macOS app are available on the Apple App Store in EU countries (excluding France).

Several governments put restrictions on the import of software containing encryption capabilities. Whether Synctrain is subject to such restrictions depends on the exact definition and interpretation of these rules. As Synctrain is a free app, we don’t have the time nor resources to go through each and every country’s specific regulations and procedures to comply. Unfortunately this means we must default to not making the app available in these countries.

France requires a specific procedure (including French-only forms to be filled in) and is therefore excluded for now. For the U.S.A., a declaration on the use of cryptography has been submitted to the BIS and we are awaiting its approval.

If you are a native speaker and resident of a country where the app is not available and you know how to help us navigate the regulatory requirements, feel free to get in touch, help is appreciated.

Is Synctrain suitable for backing up files?

Not on its own. Synctrain provides file synchronization between different devices. The main goal is to make files available on multiple locations at once, and to propagate changes to files between devices as quickly as possible. Because inadvertent changes will also be propagated as quickly as possible, this makes Synctrain by itself very unsuitable for back-up purposes. By the time you find out your precious files have been inadvertently or maliciously deleted by a virus, they will have been deleted on all peers as well.

That said, you could combine Synctrain with other solutions (such as snapshotting software or Syncthing’s versioning features) to build a proper back-up solution. It is your own responsibility to determine the requirements for a back-up system to keep your data safe, and to evaluate whether Synctrain is a suitable part for that.

Can I rely on Synctrain to keep my files safe?

Synctrain makes a best effort to handle your files are carefully as possible. Synctrain is built on Syncthing, and its number one goal is “Safe from data loss”. That said, we cannot guarantee zero data loss. While we are very careful and employ a defensive coding strategy, issues may exist in current and future Syncthing and Synctrain code. Additionally, changes in the underlying operating system, libraries or hardware may cause the app to fail in unexpected ways that we cannot always anticipate. Finally, as discussed above, issues on other devices may cause files to be deleted on a device running Synctrain (in which case Synctrain can’t really know and is simply working as designed). In no event can the authors of the app be held responsible or accountable for data loss. It is your sole responsibility to ensure you have current back-ups of all data that Synctrain may have access to. We will not help you retrieve data that was lost through the use of Synctrain: you may restore your back-up.

Why is Synctrain connecting to unknown IP addresses?

When a device you added to the app cannot be reached directly over the network, Syncthing will by default try to connect to it through relays. These are volunteer-run servers that can put two devices in connection with eachother (but cannot in any way read any data that is exchanged). You can read more about this core Syncthing feature here. To prevent Synctrain from contacting any IP address other than the ones you configure for devices, disable the relaying feature, as well as STUN and discovery in the app’s settings page.

How do I know Synctrain is secure and safe to use?

A good question, especially when you entrust the app with personal and valuable files.

Apart from taking our word for it, the only way to really know this for sure would be to audit the source code of Synctrain, Syncthing and all of the software components used by it. The full source code of Synctrain is available here for anyone to review. You may also use the source code to build the app yourself if you do not trust that binary releases match it.

Note that most of the app code concerns rather mundane user interface code (with some significant chunks related to the streaming server as well as photo synchronization). The heavy lifting, including the security-sensitive bits, is done by Syncthing (fully open source here) as well as all the packages it uses (and you’d have to trust as well). All of that is open source as well. Finally, the security of the app depends on the iOS operating systems and all the software components directly or indirectly used by the app – most of which are unfortunately not open source.

Who makes this app?

The Synctrain app is developed by me, also known as @pixelspark on GitHub. Synctrain is distributed in the Apple App Store unmodified by T-Shaped Innovatie BV. Synctrain heavily relies on Syncthing, which is developed by a team of developers.

How can I support the developers? Can I donate to the project?

Synctrain is developed primarily from a personal desire to have a well-functioning app for accessing files on the go. The app is free and it is not our intention to make money from the app.

Apart from buying me a coffee (which you can do through Github and is much appreciated!), you may consider sponsoring the Syncthing Foundation to ensure costs for e.g. server infrastructure (for global discovery, relaying, the forum, et cetera) are covered.