Microsoft has confirmed that a major worldwide outage on its Windows Azure cloud service was likely caused by a leap year coding error.
The firm's corporate vice president for cloud, Bill Laing, said in a blog post that the issue was determined "to be caused by a software bug".
"While final root cause analysis is in progress, this issue appears to be due to a time calculation that was incorrect for the leap year," he said.
The outage left customers without cloud access for between 12 and 23 hours, according to various reports.
While a fix had been pushed out in a bid to resolve the error, Laing noted yesterday that "some sub-regions and customers are still experiencing issues and as a result of these issues they may be experiencing a loss of application functionality."
The sub-regions included parts of the United States and Northern Europe, according to arstechnica.
Those problems were only completely resolved early Friday morning Australian time.
Microsoft said it would provide a full post-incident report within 10 days.
Microsoft was not the only firm to suffer leap year problems. In Australia, the HICAPS health payment service suffered issues, also allegedly due to a coding error that did not account for February 29.