SAN FRANCISCO - Twitter said a "cascading bug" caused outages Thursday affecting millions of users of the wildly popular site, and dismissed claims of a hacker attack. The outage led to a barrage of complaints and comments, some serious and other ironic, which the company said underscored "how critical Twitter has become." The on-again-off-again service led to a range of speculation and one claim of a denial of service attack, but Twitter said this was unfounded. In a blog post, Twitter vice president of engineering Mazen Rawashdeh said the company learned around 1600 GMT "that Twitter was inaccessible for all Web users, and mobile clients were not showing new tweets."
He said an investigation "found that there was a cascading bug in one of our infrastructure components. This wasn't due to a hack or our new office or Euro 2012 or GIF avatars (animation which is banned by Twitter), as some have speculated today."
Rawashdeh said a cascading bug "isn't confined to a particular software element, but rather its effect 'cascades' into other elements as well. One of the characteristics of such a bug is that it can have a significant impact on all users, worldwide, which was the case today.
"As soon as we discovered it, we took corrective actions, which included rolling back to a previous stable version of Twitter."
He said a "full recovery" was made after about two hours and that a "comprehensive review" was underway.
But the outage nonetheless provoked users to vent on other social media sites, and to tweet about it when Twitter came back up.
"Twitters broke, my life has no meaning anymore," one user wrote on the social media website Tumblr during the outage.
Another wrote, "OMG TWITTER BROKE. I feel so alone right now."
The outage caused many users to tweet about the experience when the site became accessible.
"My boss shut down Twitter because he wanted me to get back to work. Feel free to kill him if you want," one tweet said.