Description
Type: Bug
Whenever I try to connect a locally-hosted mcp to vscode for a project (inside .vscode/mcp.json), it returns the error
025-06-25 00:59:12.309 [info] Connection state: Error Error sending message to http://localhost:8000/echo/mcp: TypeError: fetch failed
2025-06-25 00:59:12.309 [error] Server exited before responding to initialize request.
or
2025-06-25 01:05:58.032 [info] Starting server echo_mcp
2025-06-25 01:05:58.033 [info] Connection state: Starting
2025-06-25 01:05:58.057 [info] Starting server from LocalProcess extension host
2025-06-25 01:05:58.058 [info] Connection state: Running
2025-06-25 01:05:58.075 [info] Connection state: Error Error sending message to http://localhost:8000/echo/mcp: TypeError: fetch failed
2025-06-25 01:05:58.075 [error] Server exited before responding to initialize request.
This doesn't happen with sse (those work perfectly)
VS Code version: Code 1.101.1 (18e3a1e, 2025-06-18T13:35:12.605Z)
OS version: Windows_NT x64 10.0.26100
Modes:
Remote OS version: Windows_NT x64 10.0.26100
System Info
| Item | Value |
|---|---|
| CPUs | AMD Ryzen 5 5600X 6-Core Processor (12 x 3700) |
| GPU Status | 2d_canvas: enabled canvas_oop_rasterization: enabled_on direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off |
| Load (avg) | undefined |
| Memory (System) | 31.93GB (14.00GB free) |
| Process Argv | --crash-reporter-id e29d6409-4089-4721-bb5b-0da52bd700a0 |
| Screen Reader | no |
| VM | 0% |
| Item | Value |
|---|---|
| Remote | programmer-pc |
| OS | Windows_NT x64 10.0.26100 |
| CPUs | 13th Gen Intel(R) Core(TM) i7-13700 (24 x 2112) |
| Memory (System) | 15.70GB (3.84GB free) |
| VM | 0% |
Extensions (52)
| Extension | Author (truncated) | Version |
|---|---|---|
| codesnap | adp | 1.3.4 |
| vscode-django | bat | 1.15.0 |
| c-cpp-compile-run | dan | 1.0.60 |
| docker | doc | 0.11.0 |
| python-environment-manager | don | 1.2.7 |
| python-extension-pack | don | 1.7.0 |
| html-preview-vscode | geo | 0.2.5 |
| copilot | Git | 1.336.0 |
| copilot-chat | Git | 0.28.2 |
| vscode-github-actions | git | 0.27.2 |
| vscode-pull-request-github | Git | 0.112.0 |
| gc-excelviewer | Gra | 4.2.63 |
| language-cython | guy | 0.0.8 |
| CppSnippets | har | 0.0.15 |
| vsc-python-indent | Kev | 1.21.0 |
| MagicPython | mag | 1.1.0 |
| rainbow-csv | mec | 3.19.0 |
| snapcode | moy | 1.1.0 |
| vscode-containers | ms- | 2.0.3 |
| vscode-docker | ms- | 2.0.0 |
| csharp | ms- | 2.80.16 |
| vscode-dotnet-runtime | ms- | 2.3.6 |
| anaconda-extension-pack | ms- | 1.0.1 |
| debugpy | ms- | 2025.8.0 |
| isort | ms- | 2025.0.0 |
| python | ms- | 2025.8.0 |
| vscode-pylance | ms- | 2025.6.1 |
| jupyter | ms- | 2025.5.0 |
| jupyter-keymap | ms- | 1.1.2 |
| jupyter-renderers | ms- | 1.1.0 |
| vscode-jupyter-cell-tags | ms- | 0.1.9 |
| vscode-jupyter-slideshow | ms- | 0.1.6 |
| remote-containers | ms- | 0.417.0 |
| remote-wsl | ms- | 0.99.0 |
| cmake-tools | ms- | 1.20.53 |
| cpptools | ms- | 1.25.3 |
| cpptools-extension-pack | ms- | 1.3.1 |
| powershell | ms- | 2025.0.0 |
| remote-explorer | ms- | 0.5.0 |
| remote-server | ms- | 1.5.2 |
| vscode-speech | ms- | 0.16.0 |
| autodocstring | njp | 0.6.1 |
| pymakr-preview | Pyc | 2.25.2 |
| sqlite-viewer | qwt | 0.10.6 |
| vscode-yaml | red | 1.18.0 |
| wav-preview | suk | 2.6.0 |
| cython | tcw | 0.1.0 |
| intellicode-api-usage-examples | Vis | 0.2.9 |
| vscodeintellicode | Vis | 1.3.2 |
| jinja | who | 0.0.8 |
| wokwi-vscode | Wok | 2.6.6 |
| vscode-sqlite3-editor | yy0 | 1.0.207 |
(2 theme extensions excluded)
A/B Experiments
vsliv368cf:30146710
vspor879:30202332
vspor708:30202333
vspor363:30204092
vswsl492:30256859
vscod805:30301674
binariesv615:30325510
c4g48928:30535728
azure-dev_surveyone:30548225
vscrp:30673768
962ge761:30959799
h48ei257:31000450
pythontbext0:30879054
cppperfnew:31000557
dwnewjupytercf:31046870
pythonrstrctxt:31112756
nativeloc1:31192215
5fd0e150:31155592
dwcopilot:31170013
6074i472:31201624
dwoutputs:31242946
customenabled:31248079
9064b325:31222308
copilot_t_ci:31333650
e5gg6876:31282496
pythoneinst12:31285622
bgtreat:31268568
4gafe986:31271826
c7cif404:31314491
pythonpulldiagcf:31325931
996jf627:31283433
pythonrdcb7cf:31303019
usemplatestapi:31297334
0aa6g176:31307128
7bj51361:31289155
747dc170:31275177
aj953862:31281341
generatesymbolt:31295002
convertfstringf:31295003
pylancequickfixt:31329274
d2249276:31332229
i851h500:31332225
usemarketplace:31333563
nesew2to4:31330641
cja58720:31331947
id45c886:31333049
nes-diff-00:31333556
test-11-treatment:31335235
gh_pad_aa_c:31335103
3cc7c867:31335119