Could not find the TLS certificate file, invalid path: (param1)

Raise code

ot isinstance(cert, basestring):
                conn.cert_file = cert[0]
                conn.key_file = cert[1]
            else:
                conn.cert_file = cert
                conn.key_file = None
            if conn.cert_file and not os.path.exists(conn.cert_file):
                raise IOError("Could not find the TLS certificate file, "
                              "invalid path: {}".format(conn.cert_file))
            if conn.key_file and not os.path.exists(conn.key_file):
                raise IOError("Could not find the TLS key file, "
                              "invalid path: {}".format(conn.key_file))

    def build_response(self, req, resp):
        """Builds a :class:`Response <requests.Response>` object from a urllib3
        response """