10/20/2020, 6:44 AM
Hi, I got the following error when fetching a bunch of images from a URL. What could be the possible reason for this? I am using prefect core. Unexpected error: ConnectionError(MaxRetryError('None: Max retries exceeded with url: /graphql (Caused by None)',),) Traceback (most recent call last): File "/usr/local/lib/python3.6/site-packages/prefect/engine/", line 48, in inner new_state = method(self, state, *args, **kwargs) File "/usr/local/lib/python3.6/site-packages/prefect/engine/", line 598, in get_flow_run_state for t in final_tasks File "/usr/local/lib/python3.6/site-packages/prefect/engine/executors/", line 446, in wait return self.client.gather(futures) File "/usr/local/lib/python3.6/site-packages/distributed/", line 1991, in gather asynchronous=asynchronous, File "/usr/local/lib/python3.6/site-packages/distributed/", line 834, in sync self.loop, func, *args, callback_timeout=callback_timeout, **kwargs File "/usr/local/lib/python3.6/site-packages/distributed/", line 339, in sync raise exc.with_traceback(tb) File "/usr/local/lib/python3.6/site-packages/distributed/", line 323, in f result[0] = yield future File "/usr/local/lib/python3.6/site-packages/tornado/", line 729, in run value = future.result() File "/usr/local/lib/python3.6/site-packages/distributed/", line 1850, in _gather raise exception.with_traceback(traceback) File "/usr/local/lib/python3.6/site-packages/prefect/engine/executors/", line 65, in _maybe_run return fn(*args, **kwargs) File "/usr/local/lib/python3.6/site-packages/prefect/engine/", line 720, in run_task flow_result=flow_result, File "/usr/local/lib/python3.6/site-packages/prefect/engine/cloud/", line 52, in init self.client = Client() File "/usr/local/lib/python3.6/site-packages/prefect/client/", line 124, in init tenant_info = self.graphql({"query": {"tenant": {"id"}}}) File "/usr/local/lib/python3.6/site-packages/prefect/client/", line 281, in graphql retry_on_api_error=retry_on_api_error, File "/usr/local/lib/python3.6/site-packages/prefect/client/", line 237, in post retry_on_api_error=retry_on_api_error, File "/usr/local/lib/python3.6/site-packages/prefect/client/", line 401, in _request session=session, method=method, url=url, params=params, headers=headers File "/usr/local/lib/python3.6/site-packages/prefect/client/", line 319, in _send_request response =, headers=headers, json=params, timeout=30) File "/usr/local/lib/python3.6/site-packages/requests/", line 581, in post return self.request('POST', url, data=data, json=json, **kwargs) File "/usr/local/lib/python3.6/site-packages/requests/", line 533, in request resp = self.send(prep, **send_kwargs) File "/usr/local/lib/python3.6/site-packages/requests/", line 646, in send r = adapter.send(request, **kwargs) File "/usr/local/lib/python3.6/site-packages/requests/", line 516, in send raise ConnectionError(e, request=request) requests.exceptions.ConnectionError: None: Max retries exceeded with url: /graphql (Caused by None)

Jim Crist-Harif

10/20/2020, 1:50 PM
Hi Chirag, this is caused by
core failing to connect to a backend (server/cloud). You say you're using "prefect core", but I assume you're also using either Cloud or Server? The connection error may be due to network issues, or an improperly configured backend api address.