fix: align JSON-RPC error response with TypeScript SDK

max-rousseau · max-rousseau · commit 40327109ed59 · 2025-12-19T10:25:17.000-08:00
Use error code -32001 (server error) and null id to match the TypeScript SDK's session not found response format. Github-Issue: #1727
diff --git a/src/mcp/server/streamable_http_manager.py b/src/mcp/server/streamable_http_manager.py
@@ -289,12 +289,15 @@ async def run_server(
                 await http_transport.handle_request(scope, receive, send)
         else:  # pragma: no cover
             # Unknown or expired session ID - return 404 per MCP spec
-            # Use JSON-RPC error format for consistency with transport errors
+            # Match TypeScript SDK exactly: jsonrpc, error, id order
             error_body = json.dumps(
                 {
                     "jsonrpc": "2.0",
-                    "id": "server-error",
-                    "error": {"code": -32600, "message": "Session not found"},
+                    "error": {
+                        "code": -32001,
+                        "message": "Session not found",
+                    },
+                    "id": None,
                 }
             )
             response = Response(

Original file line number	Diff line number	Diff line change
`@@ -289,12 +289,15 @@ async def run_server(`
`289`	`289`	`await http_transport.handle_request(scope, receive, send)`
`290`	`290`	`else: # pragma: no cover`
`291`	`291`	`# Unknown or expired session ID - return 404 per MCP spec`
`292`		`- # Use JSON-RPC error format for consistency with transport errors`
	`292`	`+ # Match TypeScript SDK exactly: jsonrpc, error, id order`
`293`	`293`	`error_body = json.dumps(`
`294`	`294`	`{`
`295`	`295`	`"jsonrpc": "2.0",`
`296`		`- "id": "server-error",`
`297`		`- "error": {"code": -32600, "message": "Session not found"},`
	`296`	`+ "error": {`
	`297`	`+ "code": -32001,`
	`298`	`+ "message": "Session not found",`
	`299`	`+ },`
	`300`	`+ "id": None,`
`298`	`301`	`}`
`299`	`302`	`)`
`300`	`303`	`response = Response(`