filesystem couldn't use the network mapped driver name, only the unc path in windows 11 23h2

[dave2nian]

Describe the bug
in my windows 11 23h2,

`C:\net use z:
Local name Z:
Remote name \davens\Multimedia
Resource type Disk
Status OK

Opens 2

Connections 1

The command completed successfully.`

claude_decktop_config.json content as below:
{ "mcpServers": { "filesystem": { "command": "npx", "args": [ "-y", "@modelcontextprotocol/server-filesystem", "Z:\\2024-MyProgramFiles" ] } } }

if I used Z: drive in the claude_decktop_config.json, z: or Z: . MCP got "Error: Parent directory does not exist: z:"

if I used the UNC path in the claude_decktop_config.json. MCP agent works well.

{ "mcpServers": { "filesystem": { "command": "npx", "args": ["@modelcontextprotocol/server-filesystem", "\\\\davens\\Multimedia\\2024-MyProgramFiles"] } } }

this problem only happen on the mapped network driver. if it is a local driver, it is fin for works.

[davpirelli]

Any update on mapped network folder?

[RalphLemarechal]

Same here

[olaservo]

Checked this against current main (post-#4638/#4631) on Windows 11.

Startup now stores both the drive-letter form of each allowed directory and its fs.realpath result, so a mapped drive is allowed under both Z:\... and the \\server\share\... it resolves to. I verified with a subst drive, which goes through the same realpath resolution as a net use mapping:

allowed = [ 'Q:\\', 'C:\\...\\CaseTest' ]
  OK  Q:\Sub\File.txt   -> C:\...\CaseTest\Sub\File.txt
  OK  q:\sub\file.txt   -> C:\...\CaseTest\Sub\File.txt
  OK  Q:\Sub\New.txt    (new file, parent exists)

The Parent directory does not exist: z:\ error in the original report came from the pre-2025 validation code, which is gone. Closing as fixed. If a Z: argument still fails on the current published version, please reopen with the exact error text and I'll look again.