New Windows 10 1809 bug: ZIP data-loss flaw is months old but Microsoft missed it

A Feedback Hub user reported the latest Windows 10 October 2018 Update bug three months ago. Microsoft has fixed the issue in preview builds of the 19H1 version of Windows 10, so it should be fixed in 1809 soon.

Windows 10 version 1809 update is still on ice due to the data-deletion bug embarrassingly missed by Microsoft during preview testing.

But the few users who did get the Windows 10 October 2018 Update have now discovered its built-in ZIP tool is doing weird things when copying files.

As one 1809 user reported on Reddit, this version of Windows 10 is missing the 'Do you want to replace these files' dialog when copying from a ZIP archive to a folder with an identically named file in it.

The problem only seems to affect the built-in ZIP tool in Windows File Explorer rather than third-party ZIP tools.

The dialog is an important flag when transferring a lot of files, since it's an opportunity for the user to choose whether to replace the identical file, skip replacing the file, or compare the information stored in both files before taking any action.

Without the dialog, it could be easy to unintentionally overwrite non-identical files.

"Pretty nasty bug since you can accidentally overwrite a file and have no way of getting it back," wrote the user.

Another Reddit user explains the same ZIP archive problem differently. When copying from ZIP, it appears as if files are being copied, and Windows File Explorer even indicates the transfer progress.

However, after it's complete, files in the destination folder have not actually been updated. Users then may delete the ZIP archive and lose their copy of files based on incorrect information.

Another Reddit user commenting on that report said: "The issue is that in 1809, overwriting files by extracting from an archive using File Explorer doesn't result in an overwrite prompt dialog and also doesn't replace any files at all; it just fails silently. There are also some reports that it did overwrite items, but did so silently without asking."

The bug does not appear to be as serious as the data-loss issues that prompted Microsoft to stop the Windows 10 1809 rollout.

SEE: 20 pro tips to make Windows 10 work the way you want (free PDF)

However, just like that bug, this newer one was also reported by a Windows Insider tester three months ago in Microsoft's Feedback Hub.

And just like the data-loss bug reports, this report failed to attract more than a few upvotes, and was subsequently missed by Microsoft during the original round of 1809 testing.

But as spotted by BleepingComputer, an engineer for Microsoft's Windows Insider Program, has confirmed this bug was fixed in the Windows 10 19H1 preview in build 18234, which was released on September 6, a month before the public release of Windows 10 1809.

That patch should mean a fix for the new bug will be available for Windows 10 1809 soon, but it's another example of Microsoft missing important feedback from testers.

Following Microsoft's 1809 data-loss debacle, the company updated its Feedback Hub to allow testers to allocate a severity rating to bug reports, which should alert Microsoft's Windows engineers to more pressing issues in future.

In the meantime, it's left the ZIP bug reporter, Jacob Klein, wondering what else he could have done to get the issue noticed by Microsoft.

"I wonder if there was anything more that I could have done when reporting that bug. I mean ... It's gotten just four UpVotes since I reported it three months ago. I filled it out as completely as I could, and did 'Recreate my problem'. I hope impact selection will help in the future," wrote Klein.

His Feedback Hub report explained the problem clearly: "Copying/pasting a file from inside a ZIP will not properly replace an existing file. Create a ZIP file that has a file in it. Have another folder available that has the same file name, but different file data. Now try to copy from insize (SIC) the ZIP file, into that other folder.

"What happens: You do NOT get the prompt to overwrite the file, the file does NOT get copied, and the files modified date DOES get updated. What should happen: You DO get the prompt to overwrite the file, the file DOES get copied (if you agree to the prompt), and the file's modified date only gets updated WHEN THE FILE IS UPDATED."

A Windows 10 insider MVP suggested reporting the issue to one of Microsoft's external Insider MVPs as their reports are given more weight than average testers.

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