Many WhatsApp users have only a month left on the service, with the instant messaging app set to end support for a range of older mobile phones at the start of 2017.
Despite announcing the news earlier this year, many users are only just becoming aware of the impending change and have taken to social media to express their panic.
The Facebook-owned company announced in February that support for older versions of Google’s Android – Android 2.1 and 2.2 and Windows Phone 7.1 will end this year.
Support for the operating systems of BlackBerry including BlackBerry 10, Nokia S40 and Symbian S60 were also initially due to end but these platforms will now be supported until June 2017.
Facebook user Raymond Mashanye posted on the social network site: “I’m one of the people who will lose,” while Mirza Lorraine said “hope mine (will) be ok”.
WhatsApp now has more than one billion users and said in their original blog post that they want to focus their efforts on the “mobile platforms the vast majority of people use.”
“While these mobile devices have been an important part of our story, they don’t offer the kind of capabilities we need to expand our app’s features in the future,” the company said.
“This was a tough decision for us to make, but the right one in order to give people better ways to keep in touch with friends, family, and loved ones using WhatsApp.”
The firm added that when WhatsApp started seven years ago more than 70% of smartphones sold at the time had operating systems offered by BlackBerry and Nokia.
But as of 2016, more than 99.5% of operating systems used on mobile devices are now offered by Google, Apple and Microsoft.
WhatsApp has recommended that those with affected devices upgrade to a newer Android, iPhone or Windows Phone before the end of 2016 to continue using the service.