When Twitter experiences an outage, users see the "fail whale" error message image created by Yiying Lu, illustrating several red birds using a net to hoist a whale from the ocean captioned "Too many tweets! Please wait a moment and try again."
Twitter had approximately ninety-eight percent uptime in 2007 (or about six full days of downtime). The downtime was particularly noticeable during events popular with the technology industry such as the 2008 Macworld Conference & Expo keynote address.
May 2008 – Twitter's new engineering team made architectural changes to deal with the scale of growth. Stability issues resulted in down time or temporary feature removal.
August 2008 – Twitter withdrew free SMS services from users in the United Kingdom and for approximately five months instant messaging support via a XMPP bot was listed as being "temporarily unavailable".
October 10, 2008 – Twitter's status blog announced that instant messaging (IM) service was no longer a temporary outage and needed to be revamped. It was announced that Twitter aims to return its IM service pending necessary major work.
June 12, 2009 – In what was called a potential "Twitpocalypse", the unique numerical identifier associated with each tweet exceeded the limit of 32-bit signed integers (2,147,483,647 total messages). While Twitter itself was not affected, some third-party clients could no longer access recent tweets. Patches were quickly released, though some iPhone applications had to wait for approval from the App Store.
September 22, 2009 – The identifier exceeded the limit for 32-bit unsigned integers (4,294,967,296 total messages) again breaking some third-party clients.
August 6, 2009 – Twitter and Facebook suffered from a denial-of-service attack, causing the Twitter website to go offline for several hours. It was later confirmed that the attacks were directed at one pro-Georgian user around the anniversary of the 2008 South Ossetia War, rather than the sites themselves.
December 17, 2009 – A hacking attack replaced the website's welcoming screen with an image of a green flag and the caption "This site has been hacked by Iranian Cyber Army" for nearly an hour. No connection between the hackers and Iran has been established.
November 2010 – A number of accounts encountered a fault that resulted in them seeing the "fail whale" when they tried to login to their accounts. The accounts themselves were not locked out as account holders could still see their "mentions" page and post from there. But the timeline and a number of other features were unavailable duri....
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