Missing partitions after installing Windows 10 Anniversary Update

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Some users have reported that after upgrading their computer to Windows 10 Anniversary Update v1607, they have discovered that one or more of their disk partitions have been lost, have disappeared or are disappearing, and the disk space is displayed as unallocated raw space in disk management.

Partitions lost or missing after upgrading from Windows 10 to v1607

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If you have just installed the update, you can reset your Windows 10 within 10 days via Settings > Update and settings > Restore > Back to previous version. If you have exceeded the 10-day time limit, you may have a situation ahead of you!

Microsoft said it is aware of the situation and asks you to be patient because it plans to release a patch to fix this problem very soon. Until then, it is recommended not to attempt to recover this data, write data to the partition(s) concerned or format the partition(s).

Thank you for your contribution and patience. Microsoft plans to release a patch to fix the majority of poorly identified partitions in a forthcoming Windows update, said a Microsoft Forum moderator on September 8

Microsoft released a cumulative update for Windows 10 v1607, KB3189866 on September 13. We hope you installed this update because it fixed the problem for many people. But there are others for whom this boring subject remains!

On September 14, a Microsoft employee on Reddit said:

Since some of you have posted happily, the problem is solved for you. And I am very happy that you are happy now 🙂 I understand that there is another group of people who have used KB3189866 but still can’t access their readers. We are still working on these variants. Please wait until these fixes apply to Windows Update. Trust us, we are actively working on it.

If KB3189866 solved your problem, great! However, if you are still facing this problem, we recommend that you wait until Microsoft has found a solution. The data is there, but the operating system can’t find it and can’t mount the partition. If you try to use third-party software, you risk losing all your data.

What was your experience with the anniversary update?

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