Twitter Inc (NYSE:TWTR) added just 4 million new users during the quarter that is surprisingly low. CFO Anthony Noto told during the earnings call that an unforeseen bug in Twitter’s integration with the iOS 8 is the main reason for the slow user growth.

How Twitter lost users?

The micro-blogging site blamed this bug for so few new users turning up. According to Noto, Twitter Inc (NYSE:TWTR) lost four million users due to this bug.

Around one million of the users, who downloaded iOS 8 never reopened Twitter or forgot their passwords due to which they could not log in, said Noto. The other three million backed from the website due to Safari’s Reader section, which no longer pings Twitter automatically for content as it did before in iOS7.

“And 3 million were on Safari, what we call auto-pulling MAUs, and we lost those,” said Noto.

Those active users of Twitter, who were readers of this app, withdrew after they updated to the iOS 8. Therefore, around three million of these users were visiting Twitter from a mobile app, but doing so unconsciously, said Noto

CEO ask investors to stay calm

Twitter Inc (NYSE:TWTR) CEO Dick Costolo confirmed that the drop in the user growth was due to the unforeseen bug. Costolo added that the company took instant step after understanding the problem to bring down its affect. However, the remedy was not the one-size fits all one, which is why there has been some complexity that triggered users going away from Twitter. The problem was complex and hurt different users in a different way, said CEO.

“There was an unforeseen bug in the release of iOS 8 as it relates to the specific Twitter integration into iOS. That’s why it was particular to us,” said Costolo.

Twitter Inc (NYSE:TWTR) told the investors to keep calm, adding that the user growth will revive in the first-quarter. CEO Dick Costolo said that early growth reports suggest that the micro-blogging site would attain the same growth it had witnessed in the first three quarters of 2014.

Despite few new users, fourth-quarter revenue of the company was better than the analyst estimates of $453.34 million, and totaled to $479 million.