Google Chrome version 50 was released to the browser's stable channel on 13 April 2016, and in addition to a handful of new features and security fixes, the update also ends support for a wide range of operating systems that have been supported since Chrome launched on those platforms. Windows XP, Windows Vista, OS X 10.6, OS X 10.7, and OS X 10.8 are no longer supported.
This is not much of a surprise, as Google indicated in November 2015 that they will end support for these older OS versions in April of 2016. Old versions of Chrome installed on these operating systems won't stop working (for now), but they'll no longer receive updates and there's no guarantee that things like Google account sign-in and data syncing will continue to work.
It is perhaps a bit of a surprise that Windows Vista will also no longer be supported as it is still officially supported by Microsoft until 2017, however with its small, shrinking market share, Google probably decided its easier to end support for Vista at the same time as the other operating systems.
Please note - This does not really affect MultiBrowser as such as we will still virtualize and make Chrome versions available as standalone browsers for testing as we have done in the past. MultiBrowser has always required Windows 7 or later to run its standalone browsers and for the application itself.