python async_error ai_generated true

AttributeError: 'coroutine' object has no attribute 'X'

ID: python/attributeerror-coroutine-no-attribute

Also available as: JSON · Markdown
95%Fix Rate
95%Confidence
200Evidence
2018-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
311 active — — —

Root Cause

Occurs when calling an async function without 'await'. The function returns a coroutine object instead of the actual result, and accessing attributes on that coroutine fails.

generic

Workarounds

  1. 97% success Add 'await' before the async function call 
    # Wrong:
result = fetch_data()  # returns coroutine
result.name  # AttributeError

# Right:
result = await fetch_data()  # returns actual data
result.name  # works

    Sources: https://docs.python.org/3/library/asyncio-task.html#coroutines

  2. 90% success If in synchronous code, use asyncio.run() to execute the coroutine 
    import asyncio
result = asyncio.run(fetch_data())
result.name  # works

    Sources: https://docs.python.org/3/library/asyncio-runner.html

Dead Ends

Common approaches that don't work:

  1. Checking if the attribute actually exists on the return type 85% fail

    The attribute exists on the actual return value, not on the coroutine wrapper. The issue is the missing 'await', not a missing attribute.

  2. Adding the missing attribute to the returned object's class 95% fail

    The returned object is a coroutine, not the intended type. Adding attributes to the class won't help because the code never reaches the actual return value.

Error Chain

Frequently confused with: