The reason? An unofficial knockoff version was released on Android. This caused some issues which the the company has "attempted to address throughout the day", it said in a statement.
There's no word on when the app will reach the other operating systems. BlackBerry says its teams "continue to work around the clock", but that it'll only launch "when it's ready and we know it will live up to your expectations of BBM."
The Android version was supposed to launch yesterday, and the iPhone version at midnight last night.
The iPhone app did go live in a few countries before BlackBerry 'paused' the rollout, to use the company's own terminology. BlackBerry's Twitter feed says the iPhone version launched in New Zealand, Australia, Malaysia, India, and UAE. "Customers who have already downloaded BBM for iPhone will be able to continue to use BBM," the statement reads.
The unofficial version for Android that caused all the headaches has been pretty popular. It's had more than 1.1 million downloads in its first eight hours, according to BlackBerry.
"As soon as we are able, we will begin a staggered country roll-out of BBM for Android and continue the roll-out of BBM for iPhone," the statement continues.
It's not been a good week for BlackBerry. It's expecting a loss of around £621 million in next week's second-quarter earnings announcement, and as such, will cut 4,500 jobs -- that's 40 per cent of its workforce. Its Z10 smart phone has sold poorly, and BB10 -- which was delayed again and again -- has struggled in the face of competition from Android and iOS.