Remove Content-Length header from MCP requests since it's disallowed by fetch#320034
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Pull request overview
This PR addresses a regression in VS Code’s MCP HTTP transport by removing the explicit Content-Length request header, which is forbidden by fetch and can cause requests to fail before any network connection is attempted. It also improves diagnostics by expanding error stringification to include nested Error.cause details.
Changes:
- Stop sending
Content-Lengthin MCP HTTP POST requests (streamable HTTP + legacy SSE) to avoidfetch-forbidden header failures. - Improve logged/error-state messages by including a limited chain of
Error.causemessages via a newstringifyError()helper.
Show a summary per file
| File | Description |
|---|---|
| src/vs/workbench/api/common/extHostMcp.ts | Removes Content-Length from MCP HTTP request headers and enhances error messages to include cause chains. |
Copilot's findings
- Files reviewed: 1/1 changed files
- Comments generated: 1
TylerLeonhardt
approved these changes
Jun 5, 2026
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