New Delhi, July 18 -- SEATTLE - When a screenshot of an AWS billing portal showing nearly $2.5 billion in estimated charges began circulating on Reddit Thursday night, the initial response was disbelief. The number was genuine, in the limited sense that Amazon's billing computation system had actually generated it. It was also wrong. The platform that processes cloud invoices for a third of the global internet had misfired, manufacturing phantom charges that bore no relationship to actual customer usage.

Amazon confirmed Friday that a bug in its billing computation subsystem had displayed dramatically inflated estimates to an unknown number of AWS customers. The company's status page attributed the failure to "a recent change" to the bil...