There were widespread reports on social media of apps crashing whenever launched on iPhones and iPads, and corresponding outage spikes on DownDetector.com.
The cause of the outages seems to have been Facebook’s software development kit, or SDK, which many apps use to manage user logins. Users don’t have to be using Facebook to log into an app for this to affect their software (they don’t even have to have it installed), and there were no reports of the same apps crashing on Android.