If you're still using WhatsApp on a BlackBerry or Windows Phone 8.0 or older then you might want to consider making the switch to Android or iOS in the near future, because the app is no longer going to be actively developed for those less popular platforms.
That doesn't mean your WhatsApp app will suddenly stop working after the cut-off point - December 31 - but it will mean you won't be able to create accounts on BlackBerry or Windows Phone, and no further updates will appear. Further down the line that's going to lead to crashes and bugs.
Windows 8.1 Mobile and Windows 10 Mobile will continue to be supported for the time being, but considering Microsoft looks to have abandoned its mobile OS platform, it's probably only a matter of time before WhatsApp disappears from here too.
'Tis the season to upgrade
"These platforms don't offer the kind of capabilities we need to expand our app's features in the future," explains a WhatsApp support note. "If you use one of these affected mobile devices, we recommend upgrading to a newer OS version."
You can't use the integrated WhatsApp backup feature to transfer your chat history between different platforms, but it is possible to email an archive of your precious conversations to yourself if you don't want to lose them - for more details head to the WhatsApp support pages.
Now owned by Facebook, it's a surprise that WhatsApp actually supported these lesser-used platforms for so long. If you have been looking for a good reason to jump ship to a different mobile OS, you've just been given another reason to do so.