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19H1 Upgrade will fail if USB or SD storage detected

Microsoft announced on their official support site on Friday that upgrade attempts to the May 2019 Update (W10 version 19H1) will fail if the target device has any USB storage devices or SD cards present. In fact, according to this support article, the upgrade might even be blocked if Windows Update detects a connected USB storage device or an SD card. The culprit is drive reassignment of external storage devices:

An external USB device or SD memory card that is attached to the computer could cause inappropriate drive reassignment on Windows 10-based computers during the installation of the May 2019 update. For this reason, these computers are currently blocked from receiving the May 2019 Update. This generates the error message that is mentioned in the “Symptoms” section if the upgrade is tried again on an affected computer.

Example: An upgrade to the May 2019 Update is tried on a computer that has a thumb drive inserted into a USB port. Before the upgrade, the device would have been mounted in the system as drive G based on the existing drive configuration. However, after the upgrade, the device is reassigned a different drive letter. For example, the drive is reassigned as drive H.

(From Microsoft Support Note “This PC can’t be upgraded . . .”)

I find it really positive that users are warned weeks before the upgrade will be rolled out. However, as the article is addressed to Windows Insiders, and according to Microsoft only applies to them. Thus, I must ask: “Why has Windows Insider team said nothing about this?” How many Insiders have made it a habit to regularly check the Microsoft Support site to see if there are new issues and / or warnings? Not many: most of us expect and trust the Insider team to tell us about any issues that are blocking updates and upgrades. I went through all of the Insider team’s social media and its Insider blog to see if this issue might be mentioned. The only thing I could find even remotely connected to this issue apppear in the Insider blog, in the release notes of build 18885 released on Friday:

General changes, improvements, and fixes for PC

We fixed an issue that could result in USBs and SD cards being unexpectedly assigned a different drive letter after upgrading.

In other words, “… we fixed an issue which we have not told you exists in the first place, and which might have caused your device being blocked, not able to upgrade.“. Version 19H1 / 1903 is already out there for Release Preview ring Insiders, some of them for sure wondering why this upgrade is not offered to them or why it fails when they manage to lay hands on it themselves.

Another confusing thing is the following sentence at the end of the support article:

Note: The drive reassignment is not limited to removable drives. Internal hard drives can also be affected.

How messed up is the current UUP method, anyway? This is at least mildly crazy.

We are all familiar when booting to WinPE that it temporarily reassigns drive letters. In such situations, the C: drive might be shown in WinPE as D: and so on. My guess is the issue now is exactly that — namely, that the offline phase of the upgrade ignores fixed drive assignments. For me, an old school geek with the habit of removing all external storage devices before an in-place upgrade, clean install or deployment, this is no big issue. But, I really would like to see Microsoft and especially the Windows Insider team make sure that this word gets out before 19H1 is officially released. To prepare for numerous posts on the Windows forums we will see after the May 2019 Update is released entitled “My upgrade failed”, I saved this short text file in Notepad:

Please remove all external USD hard disks, USB flash drives and SD cards, then try again.

I guess I will copy and paste that text quite often, sometime around the end of May. Stay tuned!


Author: Kari Finn

A former Windows Insider MVP, Kari started in computing in the mid 80’s writing code for VAX / VMS systems. Since then, he’s worked in a variety of IT positions. He specializes in Windows image capture, customization, repair and deployment as well as Hyper-V virtualization. Kari is a proud Team Member at number #1 Windows site TenForums.com.

3 Responses “19H1 Upgrade will fail if USB or SD storage detected”

  1. Toni Fasth
    April 29, 2019 at 12:11

    OMG! This is terrible. I always knew this part of Windows is a mess but didn’t know it’s this screwed up.

    • April 29, 2019 at 12:32

      What’s worrying me is the lack of information. Not a word from Insider team, only this somewhat worrying support article.

      • Toni Fasth
        April 29, 2019 at 12:43

        Yes, we have always gotten way too little information about anything regarding issues and fixes. This has always been the case, but now I feel we get even less information than before.

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