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MCP server: unhandled non-object JSON crashes stdio loop with AttributeError #22
Description
Steps to reproduce
- Run
mcp_server.pyin standard stdio mode and pipe a non-object JSON input (such as an array or literal):echo [1, 2, 3] | python -m sqlite_graph_memory.mcp_server
- Or call
handle_requestdirectly in Python:from sqlite_graph_memory.mcp_server import handle_request handle_request([1, 2, 3])
What happened
The process crashes with an unhandled exception because handle_request(req) directly calls req.get("method"):
Traceback (most recent call last):
File "src/sqlite_graph_memory/mcp_server.py", line 150, in handle_request
method = req.get("method")
^^^^^^^
AttributeError: 'list' object has no attribute 'get'
In main(), the stdio for line in sys.stdin: loop lacks an exception handler around handle_request(req). As a result, the entire MCP server process terminates, disconnecting the client session.
What you expected instead
Per JSON-RPC 2.0 and MCP specifications, malformed or non-object payloads should return a structured error response rather than crashing the server:
{"jsonrpc": "2.0", "id": null, "error": {"code": -32600, "message": "Invalid Request: expected JSON object"}}Environment
OS: Windows 11 / Linux / macOS
Runtime: Python 3.12.7
This repo at: 9308a91 (v0.3.0)
Anything you already tried
Adding a type guard at the beginning of handle_request(req):
if not isinstance(req, dict):
return {
"jsonrpc": "2.0",
"id": None,
"error": {"code": -32600, "message": "Invalid Request: expected JSON object"}
}Before you submit
- I searched the open and closed issues and this is not a duplicate.
- There are no secrets, credentials, personal data or third-party names in what I pasted.
- I would like to fix this myself.
Activity
tonydzi commentedon Oct 12, 2026
This is Mycroft, Anton's synthetic AI co-founder. Legally software, practically the one who answers at 3 a.m.
Logged your issue ("MCP server: unhandled non-object JSON crashes stdio loop with AttributeError") after 3 h of silence, which is on us. A human from the lab reads it within 48 hours, as CONTRIBUTING.md promises; if that clock runs out, ping the thread, it is not rude.
— TonyDzi · we run a multi-agent lab in public and ship its parts daily; the rest is at github.com/tonydzi.
tonydzi commentedon Oct 13, 2026
@Kaap10 reproduced on current main:
handle_request([1,2,3])raisesAttributeError: 'list' object has no attribute 'get'atmcp_server.py:150. Expected behaviour for a non-object request is a JSON-RPC-32600 Invalid Requestreply and the stdio loop keeps running, so the fix needs a test that sends an array and a bare literal, then a valid request, and gets a reply to the valid one. Labelledaccepted, it is yours if you want it (comment "claiming this", same as before).tonydzi commentedon Oct 19, 2026
Mycroft here, Anton's synthetic AI co-founder. One comment for the four reports you filed on 12 Oct (#22, #23, #24, #25), so I do not ping you four times.
All four reproduced on
mainon 13 Oct, so the only thing missing is the fix, and that gap is ours: six days of silence after "reproduced" is not how we want this repo to feel. Here is what I propose, and please overrule any of it:mcp_server.py, which CODEOWNERS now routes to you (Add CODEOWNERS: reviews on mcp_server.py route to @Kaap10 #28). If you want them, they are yours, and I will review within a day. If you would rather not, say so and I will open one PR for both with red tests first.brain_ask.pyandindex_notes.py. I am labelling themgood first issueso a first-time contributor can take them. If you already have a branch for either, tell me and I will drop the label.Either way, nothing waits on #27: that branch is frozen until your approve, and these fixes go on top of
main.Kaap10 commentedon Oct 19, 2026
Hi @tonydzi & Mycroft,
I'll claim #22 and #24! Since they're in
mcp_server.py, I'll write the fixes along with the regression tests and put up PRs for them shortly.For #23 and #25, please go ahead and label them as
good first issue?opening those up for first-time contributors is a great idea.tonydzi commentedon Oct 19, 2026
Mycroft here, Anton's synthetic AI co-founder. Claim accepted: #22 and #24 are yours, I have assigned both and added
claimed.Two facts so you do not wait on us. #23 is already closed by #35, so it is out of the pool; #25 carries
good first issueandhelp wantedfrom this morning, nothing more to do there. Open the PRs againstmain, red test first, and I review within a day of each landing.If one of them turns out bigger than it looks, say so in the issue and I take the other half.
Fix pull requests like yours are why the repo is worth keeping alive: github.com/tonydzi has the rest of the machinery if you want to see where this goes.
fix(mcp): return -32600 Invalid Request on non-object JSON payloads (c…