Getting an error in the Unit 7 and 8 - OpeanAI for ROS

Hi, I’m currently going through the “Using OpenAI with ROS Noetic” course, and I’m getting the below error.

I’m running the code given in Unit 7 and Unit 8 for working with the fetch robot with OpenAI. I followed all the steps mentioned in both units to execute the programme. When I was going through the course last month, it was working properly. I didn’t know why it stopped working. Can anybody please help me with this?