Value Error when categorical column is of dtype "Categorical"

[manujosephv]

Describe the bug
When the categorical columns are of dtype Categorical in pandas, it throws this error.
ValueError: Cannot setitem on a Categorical with a new category, set the categories first

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[DominikFilipiak]

Workaround: make sure that in your data frame all categorical columns are casted to string.

for c in cols_category:
    df[c] = df[c].astype("string") 
    df[c].fillna("na", inplace=True)