Valueerror: Cannot Convert 0 To Excel

I have a piece of code that copy/pastes data from Downloaded csv's into a predefined excel template. Some of the csv files have to be transposed before being pasted. This works wit

Solution 1:

Turned out to be the header that got created when transposing, and openpyxl didn't seem to like the 0 in there, changing for r in dataframe_to_rows(df, index=False, header=True) to header=False solved it.