azure-functions-python-worker: Failed to start language worker for: python.

I followed the steps in AzureFunctions to create a Python Function but when I tried to run it with func start I got:

func host start

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Azure Functions Core Tools (2.1.748 Commit hash: 5db20665cf0c11bedaffc96d81c9baef7456acb3)
Function Runtime Version: 2.0.12134.0
[29/10/2018 15:09:16] Building host: startup suppressed:False, configuration suppressed: False
[29/10/2018 15:09:17] Reading host configuration file 'C:\path_to_folder\Deployer\host.json'
[29/10/2018 15:09:17] Host configuration file read:
[29/10/2018 15:09:17] {
[29/10/2018 15:09:17]   "version": "2.0"
[29/10/2018 15:09:17] }
[29/10/2018 15:09:17] Initializing Host.
[29/10/2018 15:09:17] Host initialization: ConsecutiveErrors=0, StartupCount=1
[29/10/2018 15:09:17] Starting JobHost
[29/10/2018 15:09:17] Starting Host (HostId=ar2301649w1-60652735, InstanceId=b4c81e61-f576-4449-a431-1487e1f41694, Version=2.0.12134.0, ProcessId=10000, AppDomainId=1, Debug=False, FunctionsExtensionVersion=)
[29/10/2018 15:09:17] Loading functions metadata
[29/10/2018 15:09:17] 1 functions loaded
[29/10/2018 15:09:17] Starting language worker process:python  "C:\Users\ff824bv\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\python\worker.py" --host 127.0.0.1 --port 50346 --workerId e4a7da1b-b54c-4536-bbfc-333ff416d8a2 --requestId 4205ee23-e11d-409c-a957-6269517084df --grpcMaxMessageLength 134217728
[29/10/2018 15:09:17] python process with Id=19760 started
[29/10/2018 15:09:17] Generating 1 job function(s)
[29/10/2018 15:09:17] Found the following functions:
[29/10/2018 15:09:17] Host.Functions.ARM
[29/10/2018 15:09:17]
[29/10/2018 15:09:17] Host initialized (359ms)
[29/10/2018 15:09:17] Host started (369ms)
[29/10/2018 15:09:17] Job host started
Hosting environment: Production
Content root path: C:\path_to_folder\Deployer
Now listening on: http://0.0.0.0:7071
Application started. Press Ctrl+C to shut down.
Listening on http://0.0.0.0:7071/
Hit CTRL-C to exit...

Http Functions:

        ARM: [GET,POST] http://localhost:7071/api/ARM

[29/10/2018 15:09:22] Host lock lease acquired by instance ID '0000000000000000000000001960BDE6'.
[29/10/2018 15:09:23] Traceback (most recent call last):
[29/10/2018 15:09:23]   File "C:\Users\ff824bv\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\python\worker.py", line 29, in main
[29/10/2018 15:09:23] Traceback (most recent call last):
[29/10/2018 15:09:23]     args.grpc_max_msg_len)
[29/10/2018 15:09:23]   File "C:\Users\ff824bv\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\python\worker.py", line 36, in <module>
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\__init__.py", line 16, in start
[29/10/2018 15:09:23]     main()
[29/10/2018 15:09:23]     host, port, worker_id, request_id, grpc_max_msg_len))
[29/10/2018 15:09:23]   File "C:\Users\ff824bv\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\python\worker.py", line 29, in main
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\aio_compat.py", line 49, in run
[29/10/2018 15:09:23]     args.grpc_max_msg_len)
[29/10/2018 15:09:23]     return loop.run_until_complete(main)
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\__init__.py", line 16, in start
[29/10/2018 15:09:23]   File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\Lib\asyncio\base_events.py", line 468, in run_until_complete
[29/10/2018 15:09:23]     host, port, worker_id, request_id, grpc_max_msg_len))
[29/10/2018 15:09:23]     return future.result()
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\aio_compat.py", line 49, in run
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\__init__.py", line 8, in start_async
[29/10/2018 15:09:23]     return loop.run_until_complete(main)
[29/10/2018 15:09:23]     connect_timeout=5.0, max_msg_len=grpc_max_msg_len)
[29/10/2018 15:09:23]   File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\Lib\asyncio\base_events.py", line 468, in run_until_complete
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\dispatcher.py", line 74, in connect
[29/10/2018 15:09:23]     return future.result()
[29/10/2018 15:09:23]     await disp._grpc_connected_fut
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\__init__.py", line 8, in start_async
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\dispatcher.py", line 337, in __poll_grpc
[29/10/2018 15:09:23]     connect_timeout=5.0, max_msg_len=grpc_max_msg_len)
[29/10/2018 15:09:23]     timeout=self._grpc_connect_timeout)
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\dispatcher.py", line 74, in connect
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\grpc\_utilities.py", line 134, in result
[29/10/2018 15:09:23]     await disp._grpc_connected_fut
[29/10/2018 15:09:23]     self._block(timeout)
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\dispatcher.py", line 337, in __poll_grpc
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\grpc\_utilities.py", line 84, in _block
[29/10/2018 15:09:23]     timeout=self._grpc_connect_timeout)
[29/10/2018 15:09:23]     raise grpc.FutureTimeoutError()
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\grpc\_utilities.py", line 134, in result
[29/10/2018 15:09:23] Language Worker Process exited.
[29/10/2018 15:09:23]     self._block(timeout)
[29/10/2018 15:09:23] python exited with code 1
 .
[29/10/2018 15:09:23]   File "C:\path_to_folder\env\lib\site-packages\grpc\_utilities.py", line 84, in _block
[29/10/2018 15:09:23] grpc.FutureTimeoutError
[29/10/2018 15:09:23]     raise grpc.FutureTimeoutError()
[29/10/2018 15:09:23] grpc.FutureTimeoutError
[29/10/2018 15:09:23] Starting language worker process:python  "C:\Users\ff824bv\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\python\worker.py" --host 127.0.0.1 --port 50346 --workerId 6464dbe9-3adb-4651-8ac3-09be99767c45 --requestId a233668f-18f0-4934-83b3-767c77c1eb4d --grpcMaxMessageLength 134217728
[29/10/2018 15:09:23] python process with Id=19488 started
[29/10/2018 15:09:29] Traceback (most recent call last):
[29/10/2018 15:09:29]   File "C:\Users\ff824bv\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\python\worker.py", line 29, in main
[29/10/2018 15:09:29]     args.grpc_max_msg_len)
[29/10/2018 15:09:29] Traceback (most recent call last):
[29/10/2018 15:09:29]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\__init__.py", line 16, in start
[29/10/2018 15:09:29]   File "C:\Users\ff824bv\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\python\worker.py", line 36, in <module>[29/10/2018 15:09:29]     host, port, worker_id, request_id, grpc_max_msg_len))

[29/10/2018 15:09:29]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\aio_compat.py", line 49, in run
[29/10/2018 15:09:29]     main()
[29/10/2018 15:09:29]     return loop.run_until_complete(main)
[29/10/2018 15:09:29]   File "C:\Users\ff824bv\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\python\worker.py", line 29, in main
[29/10/2018 15:09:29]   File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\Lib\asyncio\base_events.py", line 468, in run_until_complete
[29/10/2018 15:09:29]     args.grpc_max_msg_len)
[29/10/2018 15:09:29]     return future.result()
[29/10/2018 15:09:29]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\__init__.py", line 16, in start
[29/10/2018 15:09:29]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\__init__.py", line 8, in start_async
[29/10/2018 15:09:29]     host, port, worker_id, request_id, grpc_max_msg_len))
[29/10/2018 15:09:29]     connect_timeout=5.0, max_msg_len=grpc_max_msg_len)
[29/10/2018 15:09:29]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\aio_compat.py", line 49, in run
[29/10/2018 15:09:29]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\dispatcher.py", line 74, in connect
[29/10/2018 15:09:29]     return loop.run_until_complete(main)
[29/10/2018 15:09:29]     await disp._grpc_connected_fut
[29/10/2018 15:09:29]   File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\Lib\asyncio\base_events.py", line 468, in run_until_complete
[29/10/2018 15:09:29]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\dispatcher.py", line 337, in __poll_grpc
[29/10/2018 15:09:29]     return future.result()
[29/10/2018 15:09:29]     timeout=self._grpc_connect_timeout)
[29/10/2018 15:09:29]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\__init__.py", line 8, in start_async
[29/10/2018 15:09:29]     connect_timeout=5.0, max_msg_len=grpc_max_msg_len)
**[29/10/2018 15:09:29] Language Worker Process exited.**
[29/10/2018 15:09:29]   File "C:\path_to_folder\env\lib\site-packages\azure\functions_worker\dispatcher.py", line 74, in connect
**[29/10/2018 15:09:29] python exited with code 1**
 .
[29/10/2018 15:09:29]     await disp._grpc_connected_fut
[29/10/2018 15:09:29]   File "C:\path_to_folder\env\lib\site-packages\grpc\_utilities.py", line 134, in result
[29/10/2018 15:09:29] Starting language worker process:python  "C:\Users\ff824bv\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\python\worker.py" --host 127.0.0.1 --port 50346 --workerId 2a2fb8fd-91d4-4f1d-910f-654aa1a980ac --requestId 146c3297-4087-4bd1-b63f-c479aa2f1be9 --grpcMaxMessageLength 134217728
[29/10/2018 15:09:29] python process with Id=8496 started

Investigative information

Please provide the following:

29/10/2018 15:09:29
Function App name Deployer
Function name(s) (as appropriate): ARM

Repro steps

Provide the steps required to reproduce the problem:

Follow the steps in AzureFunctions under Windows
Run the function with func host start / func start

Expected behavior

Provide a description of the expected behavior.

The Endpoint should start working and processing requests

Actual behavior

Provide a description of the actual behavior observed.

The error mentioned in the description
When trying to make a request I get this:

Executed 'Functions.ARM' (Failed, Id=f5dbce67-f3a9-4ca6-b558-8eddcfd83a6d)
[29/10/2018 15:14:15] System.Private.CoreLib: Exception while executing function: Functions.ARM. System.Private.CoreLib: Failed to start language worker for: python. One or more errors occurred. (python exited with code 1
 ) (python exited with code 1
 ) (python exited with code 1
 ). python exited with code 1
 .
[29/10/2018 15:14:15] Executed HTTP request: {
[29/10/2018 15:14:15]   "requestId": "74d31ed0-a540-4970-bf32-1a3b73c23814",
[29/10/2018 15:14:15]   "method": "POST",
[29/10/2018 15:14:15]   "uri": "/api/ARM",
[29/10/2018 15:14:15]   "identities": [
[29/10/2018 15:14:15]     {
[29/10/2018 15:14:15]       "type": "WebJobsAuthLevel",
[29/10/2018 15:14:15]       "level": "Admin"
[29/10/2018 15:14:15]     }
[29/10/2018 15:14:15]   ],
[29/10/2018 15:14:15]   "status": 500,
[29/10/2018 15:14:15]   "duration": 1104
[29/10/2018 15:14:15] }

About this issue

Original URL
State: closed
Created 6 years ago
Comments: 26 (6 by maintainers)

Commits related to this issue

Added QueueOutputPOJOList E2E test (#229) — committed to Azure/azure-functions-python-worker by pragnagopa 6 years ago

Most upvoted comments

For those who find this via Google and working on Windows, as mentioned above, the fix is simply to set the environmental variable NO_PROXY=localhost,127.0.0.1. The error probably occurs because you are working behind a corporate proxy and have the variables HTTP_PROXY and HTTPS_PROXY set, but not NO_PROXY. This is an issue with gRPC, see https://github.com/grpc/grpc/issues/9989.

+14

holwech on Feb 21, 2019

I’ve had a similar issue on linux, which was caused by a corporate proxy. I needed to set no_proxy environment variable for localhost/127.0.0.1

lightenup on Jan 23, 2019

It’s hard to say exactly as each person’s development environment may have slight variations that can cause issues. I see that you’re using Python installed through Visual Studio. You could try re-installing and using Python 3.6 from here: https://www.python.org/downloads/release/python-367/. I’ve encountered some issues (not necessarily Functions related) when trying to use the Python that Visual Studio provides. Feel free to post about any new/same errors you get when you make the switch and we can dig some more.

maiqbal11 on Oct 29, 2018