Solved Shared Drive Letter unavailable after update

TL;DR: After a Windows update and reboot, my D: drive letter has become unavailable. This is a problem because D: is a mounted share to a file server where all my data resides. A lot of programs depend on it being D:, so just using a different drive letter is not an option.

Details

I have two systems:

• A file server that runs Windows 10 and has 8TB hardware RAID, which is shared.
• A client Windows 11 (23H2 build 22631.5189) system that mounts the shared RAID drive as D:

My Windows 11 auto-rebooted after updating last night. It would not reconnect to the file share even after several reboots.

I deleted the mapped drive on the client (net use D: /delete) but the drive entry in This PC would not go away, so I rebooted again.

The D: drive entry on the client did go away after rebooting, but I cannot reconnect as D: In the GUI "Map Network Drive", D: is missing from the available drive letters. From the command line...


Drives T and U are smaller non-RAID drives also on the file server, and they mounted with no issues. Attempting to reconnect D: from the command line:


Also, I have a laptop also running WIndows 11 and it can mount \\home10\d as D: with no issues, so I don't believe the problem is on the file server.

How do I make D: available again?

I figured this out. For some reason, after the update and reboot, Windows decided to allocate D: and E: to empty USB drive slots, which it has never done before.

The solution was to use Disk Management to change the slots to different drive letters, freeing up D: for the share.