VSCode "Failed to fetch" local vanilla registry

[dhrapson]

Describe the bug
When I deploy a local registry and attempt to connect to it from VS Code, the message from VSC comes back as:

2026-01-19 10:09:18.047 [error] [Network] #331: http://localhost:8080/v0.1/servers?limit=50&version=latest - error GET Failed to fetch
2026-01-19 10:09:18.051 [error] [Window] Failed to fetch: TypeError: Failed to fetch
    at DSn (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:3877:37272)
    at vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:3877:38498
    at NDt.c (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:517:10759)
    at NDt.request (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:3877:38490)
    at Att.n (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:1370:16547)
    at Att.m (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:1370:16052)
    at Att.query (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:1370:13179)
    at async fmt.queryGallery (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:2597:10208)
    at async az.kc (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:2597:957)
    at async az.show (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:2595:9720)

It is unclear to me whether this is a broken MCP Registry, an incompatibility with VS Code version, or something else entirely.

To Reproduce
Steps to reproduce the behavior:

1. make dev-compose
2. configure GitHub Enterprise to allow Registry Only from http://localhost:8080
3. in VSCode -> Extensions filter for @mcp. Observe Failed to fetch popup
4. Go to VSCode -> output -> Window and observe the full stack trace

Expected behavior
Show a list of MCP servers in VSCode -> Extensions filter for @mcp

Logs
No logs from the MCP registry

Additional context
github.com/modelcontextprotocol/registry.git version: fc88cf0
VSCode version details

Version: 1.108.0 (Universal)
Commit: 94e8ae2b28cb5cc932b86e1070569c4463565c37
Date: 2026-01-08T13:53:10.781Z
Electron: 39.2.7
ElectronBuildId: 12953945
Chromium: 142.0.7444.235
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Darwin arm64 24.5.0

[rdimitrov]

Hey @dhrapson, thanks for the detailed report! Since there are no logs on the registry side, the request never actually reached it, which points to this being something in VS Code's MCP gallery client (probably HTTPS/origin restrictions on fetching a non-default gallery URL). Not really something we can dig into from this repo.

Best bet is to re-file at https://github.com/microsoft/vscode/issues with the stack trace and your registry URL setup. Closing here for now, but happy to reopen if something on our end turns out to be involved.