OneDrive users hit by file corruption bug

Users of Microsoft’s OneDrive cloud storage service have reported that files saved on the service are corrupting and failing to open.

A number of users have already flocked to Microsoft’s support forums to complain about the issue. The problem seems to lie when a file is created on a local drive in Microsoft Excel and then modified using Office Online. Once modified, when the file is reopened in Excel on a local machine, a message appears saying the “format or file extension is not valid”. However, the same file appears to be unaffected online.

One user on the forum, Dmmontal said that issue occurs after files are synced to a local computer. “They remain fine in the web app, but once they have synced, they become broken on my local computer,” the user said.

According to Mike Small, analyst at Kuppinger Cole, the problem seems only to affect Microsoft Office files which have been created or updated since around 27 August.

“This problem does not affect every device, but it can be very disconcerting when it happens to you,” he said in a blog post. Small added that if users are careful they can retrieve the file.

Small said that users could, as a workaround, log into OneDrive and download the file onto a local device to replace the corrupt copy. He added that the corrupt file should not be deleted as this sends the corrupt version to the recycle bin and will also cause the deletion of the good version on other devices.

“This example illustrates some of the downsides of using a cloud service,” said Small. “Cloud services are very convenient when they work but when they don’t work you may have very little control over the process to fix the problem. You are completely in the hands of the CSP (cloud service provider).”

Update: A Microsoft spokeswoman said: "the OneDrive team is aware of an issue that is affecting a small group of customers when they synchronise their files between devices. We are working on getting the issue resolved as soon as possible."