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Solved: Windows 7 Does Not Assign Drive Letter

October 18th, 2010 Leave a comment Go to comments

I have two sets of bays on my desktop here for connecting hard drives to this machine on a temporary basis. The bays allow me to insert either a desktop or laptop SATA hard drive into the machine for backup and/or virus repair. Suddenly and unexpectedly this week, when I put a drive in the bay, Windows 7 failed to assign a drive letter so I could not read the drive.

I am not sure what caused this, I had some trouble with an installation of Threatfire this week (which, despite what their web forum says does not coexist with Skype on a 64-bit Windows 7 installation) and I also was experimenting with Prevx. Perhaps one of these installs, or something else entirely, fouled things up but the result was that the computer would see the physical disk (it would acknowledge the drive being inserted) but could not seem to read it. If you have a similar problem, you may notice in the System Event Log and entry for the Bitlocker-Driver that says something like: Encrypted volume check: Volume information on \\?\Volume{49a0790c-28ef-11df-abb1-806e6f6e6963} cannot be read. This error is a canard as it occurs on machines, like mine, where Bitlocker isn’t even active or available for use.

As it turns out, there is a simple, if arcane fix for this problem. Open a command prompt (under accessories in the start menu, you should probably do it as administrator by right-clicking on the start menu entry), type: Diskpart then Automount Enable then exit from diskpart. Your drives should now get letters.

  1. Michael D Dirmeier
    March 24th, 2011 at 14:12 | #1

    Thank you. Seagate’s website didn’t seem to have an answer for this problem, not did any other website that I went to. This one worked for me.

  2. Dan Curcan
    June 5th, 2011 at 17:58 | #2

    Worked for me too. Thank you

  3. Jason
    August 13th, 2012 at 13:45 | #3

    THANK YOU! THANK YOU! THANK YOU!!!

    • August 13th, 2012 at 14:00 | #4

      You’re welcome. Isn’t this a nice little fix?

  4. Jason
    August 13th, 2012 at 14:43 | #5

    @admin
    Definitely was! I was beating my head against the wall trying to fix a Volume Shadow Copy error (VSS) and this ended up being the ticket!

  5. December 24th, 2012 at 08:59 | #6

    Thank you.
    Was having this probably for more than a year now.
    Have absolutaly no clue why it was turned off..
    I didn’t do it :-)

    • December 24th, 2012 at 09:03 | #7

      Who knows why this happens. Just be grateful you’re not trying to fix something on a Mac, only Steve Jobs knows how those things work and he’s dead.

  6. AdStar
    January 5th, 2013 at 18:13 | #8

    Thanks very much for this info. It solved the problem of my disappearing recovery disk as well!

  7. Phil
    June 28th, 2013 at 01:56 | #9

    I found another reason for a visible drive (in Disk Management), but no drive letter and no way to assign one.

    I was experimenting with OSL2000 (osloader.com). While that was installed, I added a new drive. Result: disk 1 shows up, but no drive letter and all actions are ghosted out, except delete volume. Solution: run the OLS2000 setup again. After reboot, the drive got assigned a letter, and the actions are available. It seems OSL2000 was hiding new drives / partitions by default.

  8. Roo
    September 11th, 2013 at 14:24 | #10

    The same problem after running Partition Wizard Pro Edition. For your consideration.

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