64-bit Firefox Stable release for Windows delayed again

Mozilla released official 64-bit versions of Firefox for Windows back in 2010. The organization made those available only to the cutting edge Nightly channel of the web browser, decided to pull those in late 2012 only to cave in and give them back a month later.

The organization announced then in 2014 that a 64-bit version of Firefox for Windows was on its way. What it meant by that was that it made the decision to build and ship 64-bit versions of Windows for Firefox's remaining channels Stable, Beta and Aurora (now Developer).

Mozilla released 64-bit versions of Firefox for Windows to the Developer and Beta channel since then but has yet to release a stable 64-bit version of Firefox for Windows.

The release was delayed several times in the past. Mozilla wanted to launch the stable 64-bit version for Windows with Firefox 39, but delayed the release because of changes it planned to ship with Firefox 41.

It then announced to release Firefox 64-bit stable for Windows when the stable channel hit version 41.

The release appears to have been delayed again however according to comments made on Mozilla's bug tracking website.

The bug, "Turn on the NPAPI process sandbox for Windows 64-bit by default" affects the deployment of the 64-bit stable version of Firefox for Windows.

The sandbox regressions only affect 64-bit Firefox users. We won't ship 64-bit Firefox until the sandbox works, so we won't be shipping 64-bit with Firefox 41 anyways.

The reason why the sandbox is needed is because 64-bit versions of Adobe Flash do not ship with a sandbox (32-bit versions ship with Protected Mode). This means that all 64-bit Firefox users on Windows are running Flash contents that are not sandboxed.

Since Mozilla cannot ship the sandbox with Firefox 41, it made the decision to delay the release of the stable version of Firefox 64-bit for Windows. The delay does not affect other 64-bit versions of Firefox for Windows.

Mozilla has yet to reveal when it plans to release the 64-bit version of Firefox Stable for Windows. The NPAPI process sandbox bug has a target milestone of Firefox 43 but that does not necessarily have to be the version in which the 64-bit version lands.