NotImplementedError In the C3_W3_A1 notebook

I have implemented both exercises in the last programming lab and successfully passed all the tests.
However during step 9 - Train the Agent, I’m receiving: NotImplementedError: Cannot convert a symbolic Tensor (sub_1:0) to a numpy array. From the code already provided in the Notebook.
I imagine the problem is still with the code I wrote but I can’t figure out where it is. As I said the code I wrote passed all the tests and I was also able to submit the notebook and received 100% grade.
However, I’d still like to be able to fully complete the lab and see the trained agent in action.

I have included the full error output here

Any help is highly appreciated.

Hello @Carlos_Julian,

Welcome to our community!

Please follow this instruction:

to use MSE that can manipulate tensor correctly in order to calculate the loss in your exercise 2.



Hi @rmwkwok thank you so much! It’s working now. I don’t know how I missed that instruction in the notebook

You are welcome @Carlos_Julian. Great job completing the last lab of this specialization!