Social networking site Twitter has recovered from an outage that left millions of members unable to access the site and post messages for up to two hours, putting the cause of the problem down to a bug in one of its infrastructure components.
ZDNet UK first noticed the outage at 17:00 BST on Thursday. It then came back online about an hour later, only to drop out again for another hour.
At around 20:20 BST, the company's official account posted a short explanation of the problem.
"Today's outage is due to a cascaded bug in one of our infrastructure components. We'll provide updated information soon," @twittercomms said.
Before the update other reports had suggested that the downtime was the result of hackers.
The website uptime checking tool downforeveryoneorjustme.com reported earlier in the day that Twitter had been widely inaccessible for intermittent periods.
While Twitter, which says it has around 140 million active members, has battled having its services blocked by authorities in certain countries, the company has had few problems with widespread downtime since its early years.