HTTP MCP Server does not work with VSCode as an MCP Client in Stateless mode #5133
Description
Bug description
Built an HTTP MCP Server using Spring AI. Works fine in Streamable mode locally though would prefer Stateless in order to be able to deploy to the cloud.
Environment
Please provide as many details as possible: Spring AI version, Java version, which vector store you use if any, etc
Spring Boot 3.5.9, Java 21, Spring AI 1.1.2 Maven project.
VSCode Version: 1.107.1 (Universal)
Commit: 994fd12f8d3a5aa16f17d42c041e5809167e845a
Date: 2025-12-17T14:15:14.850Z (4 days ago)
Electron: 39.2.3
ElectronBuildId: 12895514
Chromium: 142.0.7444.175
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Darwin arm64 25.2.0
Steps to reproduce
Run the MCP Server locally.
Connect to VSCode (Cmd + P) -> MCP: Add Server -> Enter URL Add: http://localhost:8080/mcp
Hit Start in mcp.json
Expected behavior
A clear and concise description of what you expected to happen.
Minimal Complete Reproducible example
Fails with:
Fails with error:
2025-12-21 12:27:57.295 [info] Connection state: Starting
2025-12-21 12:27:57.312 [info] Starting server from LocalProcess extension host
2025-12-21 12:27:57.312 [info] Connection state: Running
2025-12-21 12:27:57.408 [error] Error: MPC -32603: Unrecognized field "form" (class io.modelcontextprotocol.spec.McpSchema$ClientCapabilities$Elicitation), not marked as ignorable (0 known properties: ])
at [Source: UNKNOWN; byte offset: #UNKNOWN] (through reference chain: io.modelcontextprotocol.spec.McpSchema$InitializeRequest["capabilities"]->io.modelcontextprotocol.spec.McpSchema$ClientCapabilities["elicitation"]->io.modelcontextprotocol.spec.McpSchema$ClientCapabilities$Elicitation["form"])
at O8i.O (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:2265:35574)
at O8i.L (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:2265:35369)
at Sce.value (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:2265:34358)
at E.C (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:29:2349)
at E.fire (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:29:2568)
at bMs.pushMessage (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:604:55563)
at gli.$onDidReceiveMessage (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:604:52099)
at YRt.S (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:3894:40815)
at YRt.Q (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:3894:40593)
at YRt.M (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:3894:39681)