0X00000844 NERR_UnknownDevDir: Device or directory doesn't exist

You're getting error 0X00000844 (NERR_UnknownDevDir) and it's almost certainly a phantom drive mapping from an old network location. The OS keeps trying to reconnect a drive that points to a path that no longer exists.

The immediate fix

Open Command Prompt as administrator. Run:

net use

You'll see a list of all mapped network drives. Look for entries showing a status of Unavailable or whose path you don't recognize. Delete them one by one:

net use X: /delete

Replace X: with the actual drive letter. If you want to wipe them all in one shot:

net use * /delete

After that, reboot. The error should be gone.

Why this works

Windows stores persistent drive mappings in the registry under HKEY_CURRENT_USER\Network. When you map a network drive and check Reconnect at sign-in, the OS writes that mapping and tries to restore it on every login. If the target device or share gets moved, renamed, or the PC it lives on is turned off, Windows can't find it and throws 0X00000844.

The reason net use /delete works is that it removes those stale registry entries. Windows then stops trying to reconnect a dead path at boot.

Less common variations

Sometimes the error isn't from a mapped drive. It can also come from:

• Persistent mounted volume – A removable drive like an external USB or SD card that was assigned a drive letter and then got disconnected. The fix is the same: net use shows these too.
• Registry remnant from software – Some older apps (think backup tools, VPN clients) create temporary network mappings and don't clean up after themselves. Run regedit, browse to HKEY_CURRENT_USER\Network, and manually delete the keys for any drives you don't recognize. Back up the key first.
• Group Policy drive maps – If you're on a corporate domain, the mappings might come from Group Policy. In that case net use /delete won't help because the policy reapplies them on the next refresh. You'll need to talk to your IT team to fix the policy or the target server.

Prevention

Stop using Reconnect at sign-in for temporary drives. If a share is temporary, map it manually and don't check that box. For permanent shares, make sure the target machine is always reachable or use DNS names that survive IP changes.

If you regularly work with external drives on different machines, don't assign them fixed drive letters. Let Windows assign them dynamically. That way, when the drive is gone, no stale mapping lingers.