The outage comes just days after Twitter sued billionaire Elon Musk for trying to walk away from his deal to buy the company.
Twitter was down for users across the globe for almost an hour on Thursday, one of its longest outages in years.
Those attempting to use the social media platform were met with a message saying “Tweets aren't loading right now. Try again".
There were more than 50,000 incidents of people reporting issues with Twitter in the United States, according to outage tracking website Downdetector.com.
Users in other countries including the United Kingdom, Mexico, Brazil and Italy also reported issues.
According to Downdetector, users began reporting the outage around 8 am EDT (2 pm CET) and prevented users from logging into the micro-blogging site on desktops and mobile phones.
About an hour later, the service began to return.
'Thanks for sticking with us'
It was not clear what caused the outage. Twitter did not immediately respond to a request for comment.
"Some of you are having issues accessing Twitter and we’re working to get it back up and running for everyone. Thanks for sticking with us," the company said in a tweet.
Twitter's status dashboard showed it was investigating the issue with some of its application programming interfaces.
The global outage comes at a tumultuous time for Twitter, just days after it sued billionaire Elon Musk for violating his $44 billion (€43 billion) deal to buy the company.
Twitter asked a Delaware court to order the world's richest man to complete the merger at the agreed $54.20 (€54) per Twitter share.
Those who could access Twitter on Thursday jokingly blamed the outage on Musk.
"Elon Musk creates Twitter outage," one user tweeted.
'Bring back the fail whale'
Twitter was infamous for outages in its early days, and a decade ago it used its popular "Fail Whale" illustration - a beluga being lifted by birds - for such incidents.
As the platform grew, the problems became less common.
Still, Twitter suffered another widespread outage in February that disrupted services for several thousands of its users, and which it blamed on a software glitch.
Other big technology companies have also been hit by outages in the past year, with a near six-hour interruption keeping Meta Platforms' WhatsApp, Instagram and Messenger out of the reach of billions of users in October.