TypeError: cannot instantiate ctype 'EVP_MD_CTX' of unknown size

I have a script that runs gspread. It normally works fine, but now it’s throwing this exception.

I’m trying to figure out if it’s an issue with my credentials (which I don’t believe have changed, though it’s possible someone on the team did), another sudden change in Google’s API or certificates, or something else.

Either way, ideally the exception itself would be nicer.

Any ideas? Did this start happening for anyone else?

  File "app/gspread_util.py", line 56, in get_gspread_client
    gc = gspread.authorize(gspread_credentials)
  File "/app/venv/local/lib/python2.7/site-packages/gspread/client.py", line 335, in authorize
    client.login()
  File "/app/venv/local/lib/python2.7/site-packages/gspread/client.py", line 98, in login
    self.auth.refresh(http)
  File "/app/venv/local/lib/python2.7/site-packages/oauth2client/client.py", line 598, in refresh
    self._refresh(http.request)
  File "/app/venv/local/lib/python2.7/site-packages/oauth2client/client.py", line 769, in _refresh
    self._do_refresh_request(http_request)
  File "/app/venv/local/lib/python2.7/site-packages/oauth2client/client.py", line 795, in _do_refresh_request
    body = self._generate_refresh_request_body()
  File "/app/venv/local/lib/python2.7/site-packages/oauth2client/client.py", line 1425, in _generate_refresh_request_body
    assertion = self._generate_assertion()
  File "/app/venv/local/lib/python2.7/site-packages/oauth2client/client.py", line 1554, in _generate_assertion
    private_key, self.private_key_password), payload)
  File "/app/venv/local/lib/python2.7/site-packages/oauth2client/crypt.py", line 380, in make_signed_jwt
    signature = signer.sign(signing_input)
  File "/app/venv/local/lib/python2.7/site-packages/oauth2client/crypt.py", line 146, in sign
    return crypto.sign(self._key, message, 'sha256')
  File "/app/venv/local/lib/python2.7/site-packages/OpenSSL/crypto.py", line 2403, in sign
    md_ctx = _ffi.new("EVP_MD_CTX*")
TypeError: cannot instantiate ctype 'EVP_MD_CTX' of unknown size

[gw]

The cryptography package just changed.

Our temp workaround is to peg cryptography==1.4 in requirements.txt.

[jooon]

Upgrading to pyopenssl==16.1.0 will also fix this. pyopenssl has a versioned dependency on cryptography, but there is no way for cryptography to say it needs to be used by a certain version of pyopenssl (like package conflicts in debian). Pinning cryptography if you pin pyopenssl seems to be a good idea regardless.

In general I recommend http://www.kennethreitz.org/essays/a-better-pip-workflow for python app development. Pin everything that is downloaded by pip in requirements.txt for stability, but have a requirements-to-freeze.txt for actual api dependencies that your app needs.