Twitter warned users that a failed upgrade on Monday night has left the site unusable for many.
The problem began past 20:00 PDT — or 4:00am BST — and might last for hours, the company said. "Our infrastructure and operations engineers are currently working to resolve this. The site could be down until approximately 3:00am PDT," company spokeswoman Carolyn Penner said.
The Twitter status page blamed the problem on "the failed enhancement of a new approach to timeline caching". Signs of problems included the infamous 'failwhale' image indicating problems, another image signifying "something is technically wrong", missing or late tweets, duplicate tweets and a web page that did not work at times.
For more on this story, see Twitter whacked by hours-long problems on CNET News.
