title: Method not implemented!, "grpc_status":12
body: <p>I have created a GRPC service and client. Service is working and hosted on port 5001 but the client is throwing GRPC error as Method not implemented.</p>
  <p><strong>Server</strong></p>
  <pre><code>class CalculatorService(Calculator_pb2_grpc.CalculatorServicer):
  
      def SquareRoot(self, request, context):
          response = Calculator_pb2.Number()
          response.value = Calculator.square_root(request.value)
          return response
  
  
  server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
  
  Calculator_pb2_grpc.add_CalculatorServicer_to_server(
      Calculator_pb2_grpc.CalculatorServicer(),
      server)
  
  print('Starting Server on port 5001')
  
  server.add_insecure_port('[::]:5001')
  server.start()
  
  print('Server Started')
  
  server.wait_for_termination()
  </code></pre>
  <p><strong>Client</strong></p>
  <pre><code>channel = grpc.insecure_channel('localhost:5001')
  
  number = Calculator_pb2.Number(value=16)
  
  response = Calculator_pb2_grpc.CalculatorStub(channel).SquareRoot(number)
  
  print(response.value)
  </code></pre>
  <p><strong>Error</strong></p>
  <pre><code>C:\Users\anshul_jain\.virtualenvs\pythonCalc-hTzam63Y\Scripts\python.exe C:/Projects/GRPC/pythonCalc/client.py
  Traceback (most recent call last):
    File &quot;C:/Projects/GRPC/pythonCalc/client.py&quot;, line 8, in &lt;module&gt;
      response = Calculator_pb2_grpc.CalculatorStub(channel).SquareRoot(number)
    File &quot;C:\Users\anshul_jain\.virtualenvs\pythonCalc-hTzam63Y\lib\site-packages\grpc\_channel.py&quot;, line 946, in __call__
      return _end_unary_response_blocking(state, call, False, None)
    File &quot;C:\Users\anshul_jain\.virtualenvs\pythonCalc-hTzam63Y\lib\site-packages\grpc\_channel.py&quot;, line 849, in _end_unary_response_blocking
      raise _InactiveRpcError(state)
  
  grpc._channel._InactiveRpcError: _InactiveRpcError of RPC that terminated with:
      status = StatusCode.UNIMPLEMENTED
      details = &quot;Method not implemented!&quot;
      debug_error_string = &quot;{&quot;created&quot;:&quot;@1630568886.349000000&quot;,&quot;description&quot;:&quot;Error received from 
   peer \u00109\u00cc\u008f\u00a8\u0001&quot;,
      &quot;file&quot;:&quot;src/core/lib/surface/call.cc&quot;,
  &quot;file_line&quot;:1070,&quot;grpc_message&quot;:&quot;Method not implemented!&quot;,&quot;grpc_status&quot;:12}&quot;
  Process finished with exit code 1
  </code></pre>