Workflows can be cancelled during execution to stop processing immediately and free up resources. This is particularly useful for long-running workflows, background tasks, or when user requirements change mid-execution. The cancellation system provides graceful termination with proper cleanup and event logging.

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When to Use Cancellation

  • User-initiated stops: Allow users to cancel long-running processes
  • Resource management: Free up computational resources when workflows are no longer needed
  • Priority changes: Cancel lower-priority workflows to make room for urgent tasks

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Cancelling Background Workflows

For workflows running in the background (using background=True), you can cancel them using the run_id:

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Example

import asyncio
from agno.workflow import Workflow
from agno.agent import Agent
from agno.models.openai import OpenAIChat
from agno.workflow.step import Step

# Setup workflow
long_running_workflow = Workflow(
    name="Long Running Analysis",
    steps=[
        Step(name="Research", agent=Agent(model=OpenAIChat(id="gpt-5-mini"), instructions="You are a helpful assistant that can research the web.")),
        Step(name="Deep Analysis", agent=Agent(model=OpenAIChat(id="gpt-5-mini"), instructions="You are a helpful assistant that can analyze the web.")),
        Step(name="Report Generation", agent=Agent(model=OpenAIChat(id="gpt-5-mini"), instructions="You are a helpful assistant that can generate a report.")),
    ]
)

async def main():
    # Start background workflow
    bg_response = await long_running_workflow.arun(
        input="Comprehensive market analysis for emerging technologies",
        background=True
    )
    
    print(f"Started workflow with run_id: {bg_response.run_id}")
    
    # Simulate some time passing
    await asyncio.sleep(5)
    
    # Cancel the workflow
    cancellation_result = long_running_workflow.cancel_run(bg_response.run_id)
    
    if cancellation_result:  # cancellation_result is a bool
        print(f"✅ Workflow {bg_response.run_id} cancelled successfully")
    else:
        print(f"❌ Failed to cancel workflow {bg_response.run_id}")

asyncio.run(main())
When a workflow in streaming mode is cancelled, a specific event is triggered: WorkflowRunEvent.workflow_cancelled or simply known as WorkflowCancelledEvent

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