Adding Weave causes CrewAI "kickoff" to hang

[ChuckJonas]

Adding weave into my setup is causes CrewAI "kickoff" to hang indefinitely. I get a pending crewai.Crew.kickoff log that never finishes and the crew never proceeds.

Running the following code results in the process hanging after it logs the kickoff (until I kill it). Removing the weave.init and the process completes in seconds.

Reproduction Example

import dotenv
from crewai import Agent, Task, Crew, Process, LLM
import weave

dotenv.load_dotenv()

llm = LLM(model="bedrock/us.anthropic.claude-3-7-sonnet-20250219-v1:0", temperature=0.7)


def create_simple_agents():
    """Create a very simple agent for testing"""

    simple_agent = Agent(
        role="Test Agent",
        goal="Answer simple questions",
        backstory="You are a helpful test agent that provides brief answers to questions.",
        llm=llm,
        verbose=True,
        allow_delegation=False,
    )

    return simple_agent


def create_simple_task(user_query, agent):
    """Create a simple task"""

    task = Task(
        description=f"Answer this question briefly: {user_query}",
        agent=agent,
        expected_output="A brief, helpful answer to the user's question.",
    )

    return task


def test_with_weave():
    """Test crew execution with weave - this should hang"""

    # Initialize weave - this is where the problem likely occurs
    weave.init("weave-bug-testing")
    print("Weave initialized successfully")

    # Create agent and task
    agent = create_simple_agents()
    task = create_simple_task("What is 3+3?", agent)

    # Create crew
    crew = Crew(
        agents=[agent],
        tasks=[task],
        process=Process.sequential,
        verbose=True,
    )

    # Execute crew - this is where it should hang
    print("Starting crew execution with weave...")
    result = crew.kickoff()
    print(f"Result: {result.raw}")


if __name__ == "__main__":
    test_with_weave()

[jamie-rasmussen]

Thanks, we have an open ticket that sounds like it could be related - something in crewai 0.140 (or possibly its litellm dependency) seems to have introduced an infinite loop during our input serialization. A possible short term workaround is to use crewai==0.134.0