Twitter has blamed a botched software update for a fault that caused its service to become unavailable or glitchy for much of Tuesday.
The social network said an “internal code change” had led to the problem, which lasted six hours 10 minutes.
“We reverted the change, which fixed the issue,” it added.
Many of Twitter’s 300 million users were unable to log in, or if they could, were unable to make searches or post tweets during the affected period.
Twitter’s shares fell by nearly 7% following the disruption.
The BBC was later contacted by a US-based group of hackers who attempted to claim responsibility.
A spokesman from Twitter said it had “no comment” about the claim.
However, the BBC understands the company’s systems indicate there were no outside factors involved in the disruption.