Versions & Releases

Major, Minor, or Patch

Since the 1.0.0 release, Syncthing uses a semver-like 1 three part version number, x.y.z where x is the major version, y is the minor version, and z is the patch version. We decide the version number for a new release based on the following criteria:

  • Is the new version protocol incompatible with the previous one, so that they cannot connect to each other or otherwise can’t sync files for some reason? That’s a new major version. (This hasn’t happened yet.)

  • Are there changes in the REST API so that integrations or wrappers need changes, or did the database schema or configuration change so that a downgrade might be problematic? That’s a new minor version.

  • If there are no specific concerns as above, it’s a new patch version.

Release Channels

There are two different release channels that can be selected. The stable channel is the more stable one, while candidate releases are closer to development. Candidate releases get promoted to stable after a certain period of testing.

There are a few trade-offs between the two:

Stable

Candidate

Stability

More Stable

More Experimental

Features & Fixes

One month behind

Latest

Auto Upgrades

Optional

Mandatory 2

Anon. Usage Reporting

Optional

Mandatory

Support

Fully supported

Fully supported 3

Run the candidate channel if you are technically savvy and enjoy new features. Run the stable channel if you want to minimize the amount of surprises you might run into.

2

Auto upgrades are not enabled in builds delivered via APT.

3

Yes, there is intentionally no difference here.

Schedule

Barring blocking issues, stable versions are released on the first Tuesday of the month. A new candidate releases is made on the second Tuesday of the month.

How to Choose

Built-in / GitHub

For releases obtained from Syncthing.net or GitHub, with built-in upgrade functionality, the choice is made in the “Settings” dialog. Set the “Automatic upgrade” drop down to either “Stable releases only” or “Stable releases and release candidates”.

APT (Debian)

The choice between stable and candidate is done in the APT source configuration. Please see our APT instructions.

Docker

Docker images are pushed to several tags. By pulling a specific tag you can select the release channel you want:

  • syncthing/syncthing:latest points to the latest stable release, e.g. v1.9.0

  • syncthing/syncthing:rc points to the latest release candidate, e.g. v1.10.0-rc.3

  • syncthing/syncthing:nightly points to the latest nightly development build, e.g. v1.10.0-rc.3.dev.1.gd2e32957

There are also tags for the major and minor versions, for example syncthing/syncthing:1.9 for the latest stable 1.9 patch release and syncthing/syncthing:1 for the latest stable release with major version one.

Some Other Distribution Channel

If you are getting packages from your Linux distribution, NAS vendor, etc., then you should be getting the stable channel. If you get a release candidate you should complain to your distributor or vendor and refer them to this page.

Nightly Builds

It’s also possible to run the nightly development builds. These are not releases in any sense of the word, they are simply builds of the current main branch of the repository. These builds are not supported and may contain functionality that is changed or removed before the actual release.

To use nightly releases, in Advanced Settings -> Options,

  • Change “Releases URL” to https://upgrades.syncthing.net/nightly.json

  • Enable “Upgrade To Pre Releases”

Restart Syncthing and it will upgrade to the latest nightly. New nightlies are published at midnight UTC.

FAQ

What’s the relationship between candidate and release exactly?

Every new feature and bugfix begins its life in the development branch, main. Once a month the current main becomes a release candidate. This version is identified by “-rc” in its name, for example v1.5.0-rc.1.

Those running the candidate channel will update to this release candidate. For the next three weeks it is tested “in the wild”. Any new, serious issues that are discovered are fixed, and new release candidates v1.5.0-rc.2 etc are created as needed. These release candidates do not include any new features or non-essential bugfixes added to main in the meantime.

Stable releases are given version numbers without any suffix - v1.5.0. Unless any serious issues were discovered, this release is exactly identical to the “-rc.1” release candidate three weeks prior.

The cycle then restarts one week later with a new release candidate based on the current main branch.

Which bugfixes trigger a new release candidate?

Those that fix a regression since the last release. Lets say the current release is v1.5.0. We release v1.5.1-rc.1 and discover a new problem that is not present in v1.5.0. This gets fixed and we release a new v1.5.1-rc.2 candidate. However, if we discover and fix a problem that’s been present since v1.4.0, this fix will instead be incorporated in the next regular cycle.

What’s the difference between the latest candidate and the following stable release?

Nothing. If we release v1.5.1-rc.1 and no serious problems are discovered during the next twelve days, this is the exact software that will become v1.5.1 for general consumption. Since the version number is different it requires a rebuild and the release signatures / hashes are different. If you are on the candidate channel, your Syncthing will “upgrade” from v1.5.1-rc.1 to v1.5.1 when we make the release. This is normal.

—

1

SemVer-like because semver is absolutist about what constitutes an API change, in a way that isn’t super helpful to the average user of a program like Syncthing.