[SOLVED] Firebase Python AssertionError with Raspberry Pi Zero W after reboot that goes away after a few minutes

Issue

I get the following AssertionError when running my script on a Raspberry Pi Zero W after rebooting. The error stops occurring after a few minutes, and I can interface with my Firebase database as expected without issue.

However, this is still problematic because it prevents me from successfully running the script right after the device connects to wifi.

I have also posted this as an issue in the firebase-admin-python repo.

Traceback (most recent call last):
  File "/home/pi/weatherbox/48_hour_forecast.py", line 136, in <module>
    render_forecast(args.location)
  File "/home/pi/weatherbox/48_hour_forecast.py", line 88, in render_forecast
    forecast_data_48_hours.append(darksky.get_time_machine_forecast(location, timestamp_today))
  File "/home/pi/weatherbox/darksky.py", line 83, in get_time_machine_forecast
    coordinates = get_lat_long(location_search)
  File "/home/pi/weatherbox/darksky.py", line 16, in get_lat_long
    saved_location = saved_location_ref.get()
  File "/usr/local/lib/python2.7/dist-packages/firebase_admin/db.py", line 219, in get
    return self._client.body('get', self._add_suffix(), params=params)
  File "/usr/local/lib/python2.7/dist-packages/firebase_admin/_http_client.py", line 93, in body
    resp = self.request(method, url, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/firebase_admin/db.py", line 882, in request
    return super(_Client, self).request(method, url, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/firebase_admin/_http_client.py", line 84, in request
    resp = self._session.request(method, self._base_url + url, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/google/auth/transport/requests.py", line 198, in request
    self._auth_request, method, url, request_headers)
  File "/usr/local/lib/python2.7/dist-packages/google/auth/credentials.py", line 122, in before_request
    self.refresh(request)
  File "/usr/local/lib/python2.7/dist-packages/google/oauth2/service_account.py", line 320, in refresh
    assertion = self._make_authorization_grant_assertion()
  File "/usr/local/lib/python2.7/dist-packages/google/oauth2/service_account.py", line 314, in _make_authorization_grant_assertion
    token = jwt.encode(self._signer, payload)
  File "/usr/local/lib/python2.7/dist-packages/google/auth/jwt.py", line 94, in encode
    signature = signer.sign(signing_input)
  File "/usr/local/lib/python2.7/dist-packages/google/auth/crypt/_cryptography_rsa.py", line 126, in sign
    message, _PADDING, _SHA256)
  File "/usr/lib/python2.7/dist-packages/cryptography/hazmat/backends/openssl/rsa.py", line 463, in sign
    algorithm, self, data
  File "/usr/lib/python2.7/dist-packages/cryptography/hazmat/backends/openssl/rsa.py", line 241, in _rsa_sig_sign
    assert errors[0].lib == backend._lib.ERR_LIB_RSA
AssertionError

Solution

This error is specific to the Python Cryptographic Authority (PyCA) cryptography package, which is used by Firebase.

More details on this issue: https://github.com/pyca/cryptography/issues/4635

A possible workaround: https://github.com/firebase/firebase-admin-python/issues/234

Answered By - charliesneath