failwhale 300x225 Twitter timelines stopped updating hours ago. Why no word from the mothership?UPDATE: Affected Twitter accounts appear to be returning to normal. This took 12 hours (and 10 hours for Twitter to acknowledge the problem).

We stand by our argument that Twitter should have 24-hour service engineers by now – a stable service is ‘mission critical’. We’ve reached out to Twitter for comment.

Many Twitter users are experiencing a problem today – their timelines haven’t updated in hours and as of yet there’s been no word from Twitter HQ (Update: see below).

At 8.35 GMT (over six hours ago at the time of writing) new tweets dried up for me and (judging by a Twitter search) lots of other users.

Not all accounts are affected and even those who are can still happily tweet and see replies – still it’s a major problem and is crippling Twitter for many.

This is a familiar problem – Twitter has these glitches from time-to-time – but after six hours you’d have thought Twitter might have noticed and updated their Status Blog with a reassuring update that they were aware of the problem and were working on a solution. Alas no, they’re silent.

As Twitter becomes a utility for increasing numbers of people, it really can’t afford to be complacent with service faults. The fault may have emerged in the middle of a weekend night at Twitter HQ in California but do they not have 24-hour service engineers? If not, why not?

We’ll update this post when we finally hear from Twitter.

UPDATE: As a commenter has noted, Twitter Lists are still working so a workaround for the time being is to create a List of the people you’re most interested in. This List will update as usual. No news from Twitter yet, eight hours since the problem began.

UPDATE 2: 10 hours after the problem began, Twitter has just updated the Status Blog with the following: “Some users are experiencing no new updates to their timeline. We are aware of the issue and investigating.”

UPDATE3: It finally looks like affected accounts are returning to normal.