httpx.RemoteProtocolError: <ConnectionTerminated error_code:ErrorCodes.NO_ERROR, last_stream_id:0, additional_data:7b22726561736f6e223a22426164436572>

Question

I am trying to create a webservice to update a wallet pass using apns push notifications. I am using httpx for this as it can use http/2. I have the following test code for this:

import httpx
import ssl
import asyncio

async def send_push():
    context = ssl.create_default_context()
    context.load_verify_locations(cafile = "/Users/valley/Desktop/External_Finder/Learning_Centers_Development/Arcade-Pass/certs/passcertificate.pem")

    payload = {
        "aps" : ""
    }   

    async with httpx.AsyncClient(http2 = True, cert = "/Users/valley/Desktop/External_Finder/Learning_Centers_Development/Arcade-Pass/certs/ArcadePassCertKey.pem") as client:
        r = await client.post("https://api.sandbox.push.apple.com:2197/3/device/4c526af3e9cd29cc0c6f8954de5f68fd1d00348696fe4a984581e35f19fe1ddf", data = payload)
        print(r.http_version)
        print(r.text)
        
asyncio.run(send_push())

When I try to run this, I am getting the following traceback and error:

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpx/_transports/default.py", line 60, in map_httpcore_exceptions
    yield
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpx/_transports/default.py", line 353, in handle_async_request
    resp = await self._pool.handle_async_request(req)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpcore/_async/connection_pool.py", line 253, in handle_async_request
    raise exc
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpcore/_async/connection_pool.py", line 237, in handle_async_request
    response = await connection.handle_async_request(request)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpcore/_async/connection.py", line 90, in handle_async_request
    return await self._connection.handle_async_request(request)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpcore/_async/http2.py", line 146, in handle_async_request
    raise exc
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpcore/_async/http2.py", line 114, in handle_async_request
    status, headers = await self._receive_response(
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpcore/_async/http2.py", line 231, in _receive_response
    event = await self._receive_stream_event(request, stream_id)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpcore/_async/http2.py", line 262, in _receive_stream_event
    await self._receive_events(request, stream_id)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpcore/_async/http2.py", line 291, in _receive_events
    raise RemoteProtocolError(event)
httpcore.RemoteProtocolError: <ConnectionTerminated error_code:ErrorCodes.NO_ERROR, last_stream_id:0, additional_data:7b22726561736f6e223a22426164436572746966>

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "test_push_notifications.py", line 24, in <module>
    asyncio.run(send_push())
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/runners.py", line 43, in run
    return loop.run_until_complete(main)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/base_events.py", line 608, in run_until_complete
    return future.result()
  File "test_push_notifications.py", line 19, in send_push
    r = await client.post("https://api.sandbox.push.apple.com:2197/3/device/4c526af3e9cd29cc0c6f8954de5f68fd1d00348696fe4a984581e35f19fe1ddf", data = payload)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpx/_client.py", line 1848, in post
    return await self.request(
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpx/_client.py", line 1533, in request
    return await self.send(request, auth=auth, follow_redirects=follow_redirects)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpx/_client.py", line 1620, in send
    response = await self._send_handling_auth(
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpx/_client.py", line 1648, in _send_handling_auth
    response = await self._send_handling_redirects(
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpx/_client.py", line 1685, in _send_handling_redirects
    response = await self._send_single_request(request)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpx/_client.py", line 1722, in _send_single_request
    response = await transport.handle_async_request(request)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpx/_transports/default.py", line 353, in handle_async_request
    resp = await self._pool.handle_async_request(req)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/contextlib.py", line 131, in __exit__
    self.gen.throw(type, value, traceback)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/httpx/_transports/default.py", line 77, in map_httpcore_exceptions
    raise mapped_exc(message) from exc
httpx.RemoteProtocolError: <ConnectionTerminated error_code:ErrorCodes.NO_ERROR, last_stream_id:0, additional_data:7b22726561736f6e223a22426164436572746966>

Can someone please help me navigate this error and send a successful request to APNS?