Do you mean a Prefect future (from `task.submit`/`flow.submit`) or a Python `concurrent.futures`/`asyncio` future? Below is how to do it in Prefect 3.x; if you meant Python futures, I can share that too. In Prefect 3.x, a

PrefectFuture

gives you a few ways to check completion/success: - Blocking and raise on failure (simplest)

try:
    result = fut.result()  # blocks; raises on Failed/Cancelled/Crashed
    # success
except Exception as exc:
    # not successful

- Blocking and inspect the state explicitly

from prefect.schemas import StateType

fut.wait()                 # blocks until terminal state
state = fut.get_state()    # retrieve final state
if state.type == StateType.COMPLETED:
    val = fut.result(raise_on_failure=False)  # won't raise now
    # success
else:
    # not successful (Failed/Cancelled/Crashed/etc.)

- Non-blocking check (polling)

from prefect.schemas import StateType

if fut.done():             # True when in a terminal state
    state = fut.get_state()
    if state.type == StateType.COMPLETED:
        # success
    else:
        # not successful
else:
    # still running / pending

- Check for an exception without raising

exc = fut.exception()      # returns an Exception if run failed/cancelled/crashed; otherwise None
if exc is None:
    # Either still running or completed successfully — use fut.done() or state to distinguish
    if fut.done():
        # success
else:
    # not successful

- Many futures at once

from prefect.futures import wait

done, not_done = wait([f1, f2, f3])  # blocks until terminal states or timeout
for fut in done:
    st = fut.get_state()
    if st.type == StateType.COMPLETED:
        # success
    else:
        # not successful

Quick notes: -

fut.result(timeout=None, raise_on_failure=True)

blocks and raises on non-success states. -

fut.wait(timeout=None)

blocks until terminal state; it does not return the state, so call

fut.get_state()

afterward. -

fut.done()

returns True if the future is in any terminal state (Completed, Failed, Cancelled, Crashed). -

fut.exception()

returns the underlying exception if the run failed/cancelled/crashed; otherwise

None

(it may still be running, so pair with

done()

if you need to know it’s completed). If you were asking about Python

concurrent.futures

or

asyncio.Future

, let me know which one and I’ll tailor the examples.