A problem with Facebook’s auto-playing videos meant the app was running in the background and draining battery.
Facebook has admitted that its app drains iPhone batteries – but a fix is here.
The company has been investigating claims from users that the app is killing their device’s battery more quickly than usual.
Facebook engineering manager Ari Grant has admitted that two issues with the software are responsible for the problem, and that his team has now fixed them.
“The first issue we found was a ‘CPU spin’ in our network code,” he said in a Facebook post.
“A CPU spin is like a child in a car asking, ‘Are we there yet? Are we there yet? Are we there yet?’ with the question not resulting in any progress to reaching the destination.”
The second problem was with Facebook’s in-app videos, which play automatically.
Mr Grant said: “If you leave the Facebook app after watching a video, the audio session sometimes stays open as if the app was playing audio silently.
“This is similar to when you close a music app and want to keep listening to the music while you do other things, except in this case it was unintentional and nothing kept playing.”
Because it stayed awake in the background, it continued to suck the phone’s battery life.
A new update fixes the problems, he said, so users are urged to get the latest version of the software as soon as possible.
Users were alerted to the problem after installing Apple’s iOS 9 software, which shows how long apps are active and how much battery they use.