A range of apps on iPhones and iPads stopped working on Friday, with Facebook admitting it was to blame.
The firm told the BBC that “a code change triggered crashes for some iOS apps” but that the issue was “quickly resolved”.
Apps such as Spotify, TikTok, Tinder and Waze were unusable for a few hours.
Angry users took to social media while DownDetector, which monitors net blackouts, reported widespread outages.
A similar issue happened in May, affecting services for part of a day.
Of this latest failure, Facebook said in a statement: “Earlier today, a code change triggered crashes for some iOS apps using the Facebook SDK [software developer kit]. We identified the issue quickly and resolved it. We apologise for any inconvenience.”
The issues occur because app developers are encouraged to integrate the “login with Facebook” feature, in order for the social network to take advantage of the data the apps collect on users. It means that any updates will directly affect them.
The two incidents have led some to question whether Facebook has too much power over independent apps.
Writing in May after the first crash, app developer Guilherme Rambo wrote: “It was as if Facebook had an ‘app kill switch’ that they activated and it brought down many of people’s favourite iOS apps.
“Of course it was a bug and not something done intentionally, but it highlights the point that they do have control over apps that include their code.”
The problems frustrated many users, but TechCrunch’s security editor Zack Whittaker did point out advantages: “At least on the bright side, for a short while this morning none of your apps were quietly uploading your data to brokers and analytics firms without your knowledge”.
And plenty of Android users commented that their apps were “working fine”.