On my Windows 10 laptop, I sometimes need to change the letter of my external hard drives in Disk Management. Sometimes, but not always, I see the warning in Disk Management:
If you continue, the new drive letter will be assigned; but you can still use the old drive letter to access the volume until you restart your computer. The old drive letter will not be available for assignment until you restart. Warning: Changing the drive letter of a volume could cause programs to no longer run.
Which conditions/factors cause this "The old drive letter will not be available for assignment until you restart" warning to appear?
Screenshots in Disk Management:
Best Answer
I believe that “…is currently in use.” is the main factor here.
Look at this screenshot of the “Disk Management” dialog box you posted:
The key text here is“…is currently in use.”
Drive letters and drive names don’t mean much unless something is active and associated with it. As the message clearly states, the “old” drive letter is somehow still in use. Thus it is still retained for now so as not to break a supposedly active process.
Reboot and the “old” drive letter should be freed up and the new one will stay in place.
PS: And I say “supposedly active process” because the OS ultimately just wants to retain the drive letter based on what it knows: A program or process is associated with that drive letter. Whether that association is important? Not the OS’s job to say. So reboot and see what happens; most likely it will be no big deal.