From 42978c0197424450ce46ed5c3298f80404a1e13d Mon Sep 17 00:00:00 2001
From: Daniel Garnier-Moiroux <git@garnier.wf>
Date: Mon, 2 Nov 2026 15:49:22 +0100
Subject: [PATCH] HttpServletStreamableServerTransportProvider: avoid
 completing async context twice

Close the session transport instead of the async context: close() is
idempotent and swallows failures to complete the context.

Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
---
 .../HttpServletStreamableServerTransportProvider.java         | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java
index 29765a2eb..7ce830499 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java
@@ -621,7 +621,9 @@ else if (message instanceof McpSchema.JSONRPCRequest jsonrpcRequest) {
 				}
 				catch (Exception e) {
 					logger.error("Failed to handle request stream: {}", e.getMessage());
-					asyncContext.complete();
+					// The transport may already have completed the async context, when
+					// the failure comes from a message it could not send
+					sessionTransport.close();
 				}
 			}
 			else {