Twitter said on Tuesday it has resolved outages caused by a glitch in a software update that affected the social network on computers and phones, widely reported across Europe, the Middle East, Africa and North America.
In a status update at 1800 GMT, Twitter said an "intermittent issue affecting some users" was related to "an internal code change."
The statement said: "We reverted the change, which fixed the issue." There was no immediate way to determine whether full service had been restored for all users after Twitter made the change.
Both Twitter's web and mobile services began suffering outages concentrated in northern Europe around 0820 GMT, with smartphone users receiving the warning: "Tweets aren't loading right now."
Users from Scandinavia to Saudi Arabia to South Africa reported outages. India and Russia also suffered performance issues, according to a Twitter technical site.
Intermittent breakdowns later spread to the United States and Canada in the early part of their working day.
Sporadic disruptions continued at 1420 GMT, six hours after they first began to spread. At approximately 1745 GMT Twitter reported that some users were still having trouble accessing the service.
"We are aware of the issue and are working towards a resolution," a statement on the company's Twitter status website said (status.twitter.com/).
Then 15 minutes later the company announced the service problems had been resolved.
A company spokeswoman had no further comment.
Even during the outage, services had been restored for some affected users, only to fail again later. Some Twitter features continued to operate normally for some users, while others suffered disruptions, according to Twitter's developer website.
The on-again, off-again nature of the outages meant that the hashtag #twitterdown was trending as a topic while Twitter was down for many other users.
Twitter Inc shares were down almost 7 percent in afternoon trading.