# prefect-ui

Karanveer Mohan

07/25/2022, 9:35 PM
Hi, I am evaluating prefect cloud 2.0 and ran into the following
for one of my subflow runs. The cloud UI also is in an inconsistent state since it says flow/subflow is still running. It works fine locally. Any help would be appreciated!
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Encountered exception during execution:
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/prefect/", line 559, in orchestrate_flow_run
    result = await run_sync(flow_call)
  File "/usr/local/lib/python3.9/site-packages/prefect/utilities/", line 56, in run_sync_in_worker_thread
    return await anyio.to_thread.run_sync(call, cancellable=True)
  File "/usr/local/lib/python3.9/site-packages/anyio/", line 31, in run_sync
    return await get_asynclib().run_sync_in_worker_thread(
  File "/usr/local/lib/python3.9/site-packages/anyio/_backends/", line 937, in run_sync_in_worker_thread
    return await future
  File "/usr/local/lib/python3.9/site-packages/anyio/_backends/", line 867, in run
    result =, *args)
  File "/root/deployer/", line 21, in run_ro
  File "/usr/local/lib/python3.9/site-packages/prefect/", line 367, in __call__
    return enter_flow_run_engine_from_flow_call(
  File "/usr/local/lib/python3.9/site-packages/prefect/", line 154, in enter_flow_run_engine_from_flow_call
    return run_async_from_worker_thread(begin_run)
  File "/usr/local/lib/python3.9/site-packages/prefect/utilities/", line 136, in run_async_from_worker_thread
  File "/usr/local/lib/python3.9/site-packages/anyio/", line 49, in run
    return asynclib.run_async_from_thread(func, *args)
  File "/usr/local/lib/python3.9/site-packages/anyio/_backends/", line 970, in run_async_from_thread
    return f.result()
  File "/usr/local/lib/python3.9/concurrent/futures/", line 445, in result
    return self.__get_result()
  File "/usr/local/lib/python3.9/concurrent/futures/", line 390, in __get_result
    raise self._exception
  File "/usr/local/lib/python3.9/site-packages/prefect/", line 104, in with_injected_client
    return await fn(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/prefect/", line 454, in create_and_begin_subflow_run
    terminal_state = await orchestrate_flow_run(
  File "/usr/local/lib/python3.9/", line 670, in __aexit__
    raise exc_details[1]
  File "/usr/local/lib/python3.9/", line 653, in __aexit__
    cb_suppress = await cb(*exc_details)
  File "/usr/local/lib/python3.9/", line 199, in __aexit__
    await self.gen.athrow(typ, value, traceback)
  File "/usr/local/lib/python3.9/site-packages/prefect/", line 1181, in report_flow_run_crashes
    await client.set_flow_run_state(
  File "/usr/local/lib/python3.9/site-packages/prefect/", line 1505, in set_flow_run_state
    response = await <|>(
  File "/usr/local/lib/python3.9/site-packages/httpx/", line 1842, in post
    return await self.request(
  File "/usr/local/lib/python3.9/site-packages/httpx/", line 1527, in request
    return await self.send(request, auth=auth, follow_redirects=follow_redirects)
  File "/usr/local/lib/python3.9/site-packages/prefect/", line 277, in send
  File "/usr/local/lib/python3.9/site-packages/prefect/", line 223, in raise_for_status
    raise PrefectHTTPStatusError.from_httpx_error(exc) from exc.__cause__
prefect.exceptions.PrefectHTTPStatusError: Server error '503 Service Unavailable' for url '<>'
For more information check: <>
02:01:18 PM
Crash detected! Execution was interrupted by an unexpected exception.


07/26/2022, 1:00 PM
Hi @Karanveer Mohan - thanks for the question. I'm checking with the team on this one.

Anna Geller

07/26/2022, 1:09 PM
Can you upgrade Prefect to the latest version? This should fix your issue:
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pip install -U "prefect>=2.0b"

Karanveer Mohan

07/26/2022, 8:30 PM
thank you! will report back if the issue happens again 🙏
👍 1
🙌 1
FYI, my pipelines failed last night on 2.0b14 with the following error:
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PrefectHTTPStatusError: Client error '400 Bad Request' for url '<>'
Response: {'detail': 'The request specified API version 0.7.0 but this serverrequires version 0.8.0 or higher.'}
I updated to 2.0b15 today and it seems to have fixed it. Just an FYI for others 🙂
🙌 2