Microsoft has admitted that a second bug made it into the Windows 10 October 2018 Update that could result in data loss.

Windows 10’s October 2018 major feature update was only available for six days before it was pulled due to a file-wiping bug.

The bug deleted files stored in the user’s Documents and Pictures folders, resulting in the loss of years’ worth of files on some PCs.

Now Microsoft has confirmed the update contains a second flaw that, while more minor than the original, could also lead to data being lost.

SEE: Windows 10 power tips: Secret shortcuts to your favorite settings (Tech Pro Research)

The bug occurs when copying or moving compressed files from a .ZIP folder to a regular or protected folder.

As a Microsoft support agent explained:

“There is a known issue in the Windows 10 October Update where the consent prompt ‘Do you want to replace these files’ is missing when copying contents from a .ZIP file,” the agent wrote.

“With the Windows 10 October 2018 Update, if you copy or move files from a .ZIP file (without first ‘extracting’ the contents) in to a new destination folder that contains duplicate filenames or is write-protected, you don’t get a ‘Do you want to replace these files’ prompt. It will appear that the files were overwritten, when in fact the copy action for those files is not executed and files have not been overwritten.”

While copying the files from the .ZIP folder will silently fail, cutting and pasting the files from such a folder could “result in unintentionally deleting items that may not be recoverable”, the agent said.

If files were lost after being moved from a .ZIP folder, the agent said they should be able to be recovered from the Recycle Bin or from the Temporary File Directory, following the steps outlined here. The agent says a patch for the problem is due in November.

As with the previous file-wiping bug, it appears this new flaw was also reported by a Windows Insider tester months ago in the Microsoft’s Feedback Hub.

As TechRepublic’s sister site ZDNet points out, this latest bug report was also not picked up by Microsoft during the original round of testing for the October Update, likely due to it only attracting a few upvotes.

Some users of the October Update, known as build 1809, also reported a bug that caused Task Manager to report the incorrect CPU utilization. A subsequent fix for the 1809 build resulted in some HP systems suffering from the Blue Screen of Death due to driver issues, which in turn triggered another update to fix issues with driver compatibility.

In the wake of the October Update rollout being halted, Microsoft has faced calls to slow the pace at which major feature updates are applied to Windows 10 to ensure new releases are more stable. For its part, Microsoft has introduced a way for those testing early builds of the OS under the Windows Insider Program to flag the severity of bugs.

Microsoft has said it is making progress on fixing bugs in the October update, ahead of resuming its rollout.

The big takeaways for tech leaders:

  • Microsoft has confirmed the Windows 10 October 2018 Update suffers from a bug when copying and moving compressed files from .ZIP folders.
  • The rollout of the Windows 10 October 2018 Update was halted after six days due to the discovery of a file-wiping bug.

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