Popular smartphone apps including Spotify and Pinterest suffered outages Friday for a few hours due to a bug in Facebook's systems.

Facebook has resolved the problem, a spokesperson said.

"Earlier today, a code change triggered crashes for some iOS apps using the Facebook SDK," or software development kit, the spokesperson said. 

"We identified the issue quickly and resolved it. We apologize for any inconvenience."

App users began reporting on Twitter early Friday that they were unable to open Spotify and other sites. 

Downdetector, which monitors for internet problems in real time, showed a rise in problems for a number of applications, including Spotify, Pinterest, Waze and The New York Times.

It reported a major spike in problems around 1030 GMT, and a decline in user issues at around 1300 GMT.