Update (May 8 10:20 UTC): Mozilla released Firefox 52.1.1esr fixing among others a security bug which could lead to a potentially exploitable crash on the Windows platform. By default Tor Browser users are not affected as WebGL is put behind click-to-play placeholders, thanks to NoScript. Nevertheless, we are preparing a release later this week picking this fix up and, in addition to that, a lot of other improvements for our alpha series.

Update (Apr 24 8:36 UTC): Thanks to all for testing this alpha release so far. It turns out there are a number of issues that are affecting a lot of our alpha users. The following list should give an overview and help to avoid duplicate bug reports:

Tor Browser is crashing when opening/downloading files that need an external application to handle them. This is bug 21766.

Tor Browser is crashing on about:addons with the security slider set to "high" and does not show any preferences on about:preferences ticked. This issue is tracked in bug 21962.

The canvas prompt is not shown anymore in Tor Browser. This issue is tracked in bug 21778.

There is no sound on Linux systems without PulseAudio anymore. This is bug 1247056. Check this one out for Mozilla's reasoning behind dropping ALSA support.

Tor Browser 7.0a3 is now available from the Tor Browser Project page and also from our distribution directory.

This release features important security updates to Firefox.

This is the first alpha release which is based on Firefox ESR 52. We updated all of our patches that did not get upstreamed yet and made Torbutton and Tor Launcher multiprocess (e10s) compatible. After the first nightly build based on ESR52 went out we already fixed a number of bugs associated with this switch. But more remain, please help!

We hope having e10s and Mozilla's content sandbox enabled will be one of the major new features in the upcoming Tor Browser 7.0 series, both security- and performance-wise. While we are still working on the sandboxing part for Windows, both Linux and macOS have e10s and content sandboxing enabled by default in Tor Browser 7.0a3. There are already a number of bugs related to that on our radar which can be found on our bug tracker and which are tagged with the `tbb-e10s` keyword. If you find more, please report them!

The switch to Firefox ESR 52 raises the system requirements for Tor Browser on Windows and macOS. Computers running Windows and are not SSE2-capable are not supported anymore. On Apple computers with OS X < 10.9 Tor Browser won't run anymore either. Update (Apr 24 8:41 UTC): Only the browser part of Tor Browser is affected by these new constraints. If you are e.g. on Windows and are using the expert bundle or are extracting tor from Tor Browser it should run on any computer it used to run. The same holds for macOS with one exception: tor we ship in Tor Browser won't run on Apple computers with OS X 10.6 anymore either.

We updated our toolchains during the ESR transition as well. In particular we retired the old GCC-based one for our macOS cross-compilation and rely solely on clang/cctools now. As with previous releases building 7.0a3 is fully reproducible on all three supported platforms, even though we needed to deploy a last minute patch for Linux bundles this time.

Apart from switching to the new ESR and dealing with related issues we included a new Tor alpha (0.3.0.5-rc) and updated our NoScript (5.0.2) and HTTPS-Everywhere versions (5.2.14). The Sandboxed Tor Browser for Linux got updated to 0.0.6 making sure it is compatible with Firefox ESR 52.

As in Tor Browser 6.5.2 we provide a fix for Tor Browser crashing on github.com on Windows and for Twitter issues that got reported already a while ago. We update our security slider as well taking newer JIT preferences into account.

A note to Windows users: We signed the .exe files with a new codesigning certificate as the old one is about to expire. If there are issues with that new certificate, e.g. scary warnings showing up after downloading a Tor Browser .exe file and double-clicking on it, please let us know.

The full changelog since Tor Browser 7.0a2 is: