Some users experiencing trouble with external USB drives after upgrading to Windows 10 Anniversary Update (Version 1607). The external disk is no longer recognized.
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I've found several reports in German Microsoft Answers forums, where users are claiming this issue. After upgrading to Windows 10 Version 1607, the external USB disk (or USB thumb drive) is no longer detected. In disk management console, the drive is shown either as RAW or unallocated. In a tenforums.com thread, a user posted the following screen shot.
All users are reporting, that the USB disks works on other systems like Windows 7, 8.1 or Windows 10 up to Version 1511. Also a rollback from Anniversary Update to Windows 10 Version 1511 brings the external USB disk back to live. Some users are reporting, that the drive is reported as RAW disk. Then chkdsk detects the drive as NTFS formatted (see).
Not all users are affected and some solutions
From what I found out so far, the problem doesn't hit all users of Windows 10 Version 1607. I've tested two of my machines with Windows 10 Version 1607 and an external USB 3.0 hard disk. Both machines detects the hard disk as expected.
Microsoft has released a note Partitions may be missing after installing the Anniversary Update in Microsoft Answers forum, that they aware of an issue. But I'm not sure, whether this is helpful. Some people reporting that reformatting the USB disk brought it back to life under Windows 10 Version 1607. The only fix till yet is a rollback to Windows 10 Version 1511.
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A Microsoft employee confirms the issue for some external disks. It could be related to the system's mainboard. There are also reports, that updates KB3176936 and KB3176934 has fixed the issue for some users. But it seems that the error has several causes. Here is a screenshot from a forum showing a disk partition a RAW.
This user reported that he was able to fix his issue using a third party tool an this guide has brought his unallocated drive back to Windows. But in the US MS Answers forum is a lengthy thread, where users are trying different things (also exchanging drivers) without success.
In this MS Answers thread Microsoft employee Mahesh Dudgikar confirms, that KB3176934 doesn't has a fix for the RAW format but. His post, dated from August 24, 2016, quotes, that MS has identified the problem. They intend to send the fix to several machines before a global rollout via Windows Update is made. Maybe this explains, why some people sees that an update has fixed the issue and others are left with a broken device.
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Bugs in Windows Disk Management tool
Windows 10-Upgrade: "Disk Controller: Current Active partition is compressed"
PSA: Windows 10 Anniversary Update gives just 10 days for rollback
