Facebook Messenger and Instagram all appear to have stopped working for some users.
The trio of Facebook-owned apps mysteriously went down on Thursday morning, according to frustrated users.
Online outage tracker Down Detector logged thousands of complaints from just after 10am UK time.
Most of the issues seem to relate to Facebook Messenger.
But some users are also moaning that Facebook proper and Instagram have stopped working too.
The outage doesn’t appear to be affecting all users – but it’s severe for those affected.