Twitter added a total of four million new users last quarter, a number that seems surprisingly low.
During the company’s earnings call, CFO Anthony Noto provided an excuse for its lack of growth: An “unforeseen bug” in Twitter’s integration with iOS 8, Apple’s mobile software update that launched in September. This “bug” caused Twitter to lose four million users, he added, or half of the company’s actual growth.
How exactly does that work?
Well, one million of those users were people who downloaded iOS 8 and either never reopened Twitter, or forgot their password and couldn’t log back in. The other three million were lost due to Safari’s Reader section, which no longer pings Twitter automatically for content like it did in iOS 7. Users who were counted as active because of this automatic pinging on iOS 7 were then lost when they updated to iOS 8.
So three million of these lost users were accessing Twitter from a mobile browser and really weren’t accessing Twitter at all (at least not consciously). They were counted as “active” because Safari did the work for them.
So that’s how Twitter lost four million users, although it sounds like it was more about the update to iOS 8 than a bug.
Twitter told investors not to worry, however; growth numbers will rebound in Q1. CEO Dick Costolo said that early growth reports the company is collecting mean Twitter should be back to the kind of growth it had for the first three quarters of 2014 — an average of more than 14 million new users per quarter.
That explanation, and a solid financial quarter from the company, helped push Twitter stock up more than 10 percent in after-hours trading.
Update: Twitter walked back CEO Dick Costolo’s comment from yesterday describing the drop in users as the result of an “unforeseen bug” in iOS 8. Twitter now says it was “no bug” but a situation on their end. We reported as much above, but now it’s been said more clearly from Twitter.
This article originally appeared on Recode.net.