The function to_excel of pandas generate an unexpected TypeError

Question

I created a dictionary of pandas dataframe:

d[k] = pd.DataFrame(data=data[i])

So I assume that d[k] is a correct pandas dataframe.<

Answer 1

I have same problem with openpyxl=3.0.2,

Refer to this answer, I roll openpyxl back to 3.0.1(conda or pip) and it works.

>>> conda remove openpyxl
>>> conda install openpyxl==3.0.1

or

>>> pip uninstall openpyxl
>>> pip install openpyxl==3.0.1