Twitter - infamous for its "fail whale" outage messages in its early years - went dark for hours on June 21. On Thursday, users trying to log on to its website were greeted only by an incomplete error message: "Twitter is currently down for. We expect to be back in."
"Users may be experiencing issues accessing Twitter. Our engineers are currently working to resolve the issue," the San Francisco-based company wrote in a blog post shortly after 8:30 am Pacific time (2100 IST).
The June episode revived fears that stability issues may once again be plaguing Twitter, which claims to have significantly improved its infrastructure. The company blamed that incident on a "cascading bug".
Chief Executive Dick Costolo, who has focused on improving the service's profitability and attracting advertisers, said last month that Twitter has 140 million active monthly users who send 400 million tweets daily.
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