Several iOS users are apparently experiencing issues with Apple's iMessage app since last night, while some users are unable to access the service completely for some reason. Given the intermittent service outages, some users are unable to access the blue bubble conversation or send iMessages, and instead they are being redirected to standard green-bubble text messages.
Macrumors reports that only some iPhone and iPad users are affected by this issue and it is not a widespread problem. There have been numerous complaints reported on Twitter by all affected iMessage users, while Apple is yet to react to this situation.
Nevertheless, Apple's System Status page is currently showing green lights signalling that the service is fully active without any instance of outages with any of the services including iMessage.
Consequently, the root cause of the problem is still unknown even as affected users are eagerly awaiting an update or probably a fix from Apple.