A leaked OS for all BlackBerry 10 devices dropped on us yesterday. While many people are comfortable with the process of installing leaked OS, there are also many who don't or would much rather install stock OS. If you are part of the latter crowd and you have a Vodafone SIM card handy, then you can get the OS 10.2.0.1803 update OTA.
Taking a look at the forums it looks like it's available for all BlackBerry 10 devices, including the BlackBerry Z30. The software version will show as 10.2.0.429 but you should end up with OS version 10.2.0.1803. This is a pretty fast update, seeing as we only recently saw BlackBerry OS 10.2 arrive in the U.K. and other parts of the world. Not sure what's new but seeing as the BlackBerry Z30 didn't get the 10.2.0.1791 update, this version will at least bring the dark theme option to Z30 owners.
Don't forget, even if this is an official update, it's always best to carry out a backup via BlackBerry Link.