Microsoft has acknowledged that Windows version 1809 is incorrectly missing the 'Do you want to replace these files?' prompt, when copying contents from a .ZIP file to another folder with identically named files.
It's an omission that has affected the few users who managed to install Windows 1809 before Microsoft halted the rollout to fix its disastrous data-loss bug.
They recently discovered that Windows 1809 was not warning them when moving files from a .ZIP archive to a regular folder with duplicate filenames.
Also, users reported that files that should have been copied didn't actually get copied to the destination folder, and there was no indication that the action wasn't carried out. As one user put it, Windows file copying just "silently failed".
Microsoft has now offered a explanation of what exactly is going on via its answers forum, and detailed a workaround to the problem of files not copying. Microsoft is aiming to patch the issue in November.
Until the patch arrives, the key to ensuring that files do get copied while this bug exists is to extract the files from the .ZIP folder first, and then copy the files to the destination folder. The copy action fails when copying directly from a compressed folder.
The company also warned against using Cut and Paste to move items from a compressed (.zip) folder because users may not be able to recover files lost during the process.
In the case of copying, no files are overwritten, while moving files will silently fail but also might remove or delete the moved file.
Microsoft details how to restore deleted files from the Recycle Bin and the Temporary File Directory.
SEE: 20 pro tips to make Windows 10 work the way you want (free PDF)
This bug is another example of an apparently known error slipping through Microsoft's testing processes.
As this reporter noted, a Windows Insider flagged the ZIP bug through Microsoft's Feedback Hub three months ago, a few weeks before general availability of version 1809.
Microsoft even fixed this bug in a 19H1 preview build that was released a month before 1809 was available to all.
Microsoft's decision to pull the 1809 update over the data-loss bug -- and its failure to spot several Windows Insider reports about the issue during preview -- has bolstered arguments by IT pros that Microsoft needs to fix the quality of its updates, and give Windows 10 Home users a way to opt out of at least the April updates.
Besides data-loss problems, 1809 was released with known incompatibility issues with Intel and HP drivers.
As ZDNet's Mary Jo Foley argued after 1809 was pulled, Microsoft should make one of its twice-yearly major releases exclusively focused on reliability issues and not new features.
"Go back to basics and figure out what's not working before continuing headlong down the 'we have hundreds of new features' path," she wrote.
"Figure out how to better test OneDrive and Windows 10 together. Work with OEMs to figure out how they can release updated drivers simultaneously with new feature updates, when required."
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 October update's new public rollout nears as Microsoft fixes more bugs
Microsoft finds and fixes more glitches in Windows 10 October 2018 Update.
Windows 10 audio problems? Intel issued buggy driver but we fixed it, says Microsoft
Intel accidentally pushed an incompatible audio driver to Windows 10 devices through Windows Update.
More Windows 10 October update woes? HP users report BSOD after Tuesday patch
Admins struggle with the latest Windows 10 1809 patch on some HP systems.
Windows 10 1809 bungle: We won't miss early problem reports again, says Microsoft
Microsoft makes changes to its Feedback Hub after failing to notice early reports flagging up data losses caused by the Windows 10 October 2108 Update.
Microsoft halts rollout of Windows 10 October 2018 Update: What happens next?
Only days after releasing its latest feature update to Windows 10, Microsoft abruptly stopped the rollout and pulled the new version from its download servers as it investigates "isolated reports" of a data-destroying bug. What should you do now?
Windows 10 October update delete your files? This tool might recover them
No word yet from Microsoft about Windows 10 October 2018 Update deleting user files -- but it's a problem Windows Insiders have encountered before.
Windows 10 October update problems: Wiped docs, plus Intel driver warning
Back up files before upgrading to Windows 10 1809, and if you get a warning about Intel drivers, do not proceed.
Microsoft begins rolling out Windows 10 October 2018 Update
Microsoft is starting to roll out the Windows 10 October 2018 Update today, starting with Insiders and those ready to proactively grab the new bits.
Windows 10 1809: Microsoft reveals features it's dropping in October 2018 Update
Microsoft sets out its list of features that are being removed or deprecated in the next Windows 10 release.
Windows 10 October 2018 Update: The new features that matter most
Windows 10 version 1809, officially the October 2018 Update,started rolling out October 2. Here are some of the new capabilities you can expect in this surprisingly feature-packed release.
Windows 10 October 2018 Update: 5 new features business users will love TechRepublic
Windows 10 is getting a big update in its next release. Here are some of the enterprise-centered features to expect in the Windows 10 October 2018 Update.
Surface Pro 6, Surface Laptop 2, Surface Studio 2 and Surface Headphones: Everything Microsoft just announced CNET
Plus: Windows 10 October 2018 Update is now available.