Twitter experienced a bevy of glitches as links stopped working, some users were unable to log in and images failed to load for others.
The company, which has experienced an uptick in instability and bugs in recent months after Elon Musk cut its staff sharply, said: “Some parts of Twitter may not be working as expected right now.
“We made an internal change that had some unintended consequences.
“We’re working on this now and will share an update when it’s fixed.”
Trying to visit Twitter’s help page on Monday led to an error message saying: “Your current API plan does not include access to this endpoint”.
It displayed a link to a software developer page that also did not work.
Internet access watchdog NetBlocks said: “Twitter is currently experiencing international slowdowns and outages affecting many users.”
It said image and video content was also affected.
Some users were not able to see the images other users were posting.
At 6.05pm UK-time, Twitter’s support account said: “Things should now be working as normal. Thanks for sticking with us!”
Twitter engineers and experts have been warning the platform is at an increased risk of fraying since Musk fired most of the people who worked on keeping it running.
Last month, a bug left users unable to send tweets.