Programming assingment error" There was a problem compiling the code from your notebook"

Course Q&A TensorFlow Developer Professional Sequences, Time Series and Prediction
1

There was a problem compiling the code from your notebook. Details:
unsupported operand type(s) for +: ‘float’ and ‘NoneType’ .

i am getting this error in all the code blocks

2

code is running fine getting this error in Grades

3

nevermind reloading seem to have fixed it idk

4

Tip: Always save your notebook manually (using the Save icon) before you submit it for grading.