From d69e57faf6ed17cdf7af25893bbc8d8b59f722f2 Mon Sep 17 00:00:00 2001 From: mayuriphad Date: Sun, 23 Aug 2026 21:26:06 +0530 Subject: [PATCH] Fix ClientSession swallowing exceptions in default message_handler --- src/mcp/client/session.py | 3 +++ 1 file changed, 3 insertions(+) diff --git a/src/mcp/client/session.py b/src/mcp/client/session.py index f18cc0ef10..4f80cbb7af 100644 --- a/src/mcp/client/session.py +++ b/src/mcp/client/session.py @@ -250,6 +250,9 @@ async def __call__(self, message: IncomingMessage) -> None: ... # pragma: no br async def _default_message_handler(message: IncomingMessage) -> None: + if isinstance(message, Exception): + logger.error("ClientSession Error: %s", message) + raise message await anyio.lowlevel.checkpoint()