AttributeError: 'Nonetype' while creating dataframe using pandas

Question

I am fetching data from database, and converting it to dataframe using pandas. I am getting AttributeError.

Code:

    conn = adodbapi.connect("Provider=SQLNCLT11, Sever=LDN209232, Database = mydb, Integrated Security = SSPI, 180")
    cursor = conn.cursor()
    
    cursor.execute("select rowId, businessDate from mydb.mytable")
    data = cursor.fetchall()
    ar=astype("str")
    df = pd.Dataframe(ar).transpose()
    ar.astype('str')
    df.columns = data.columnNames.keys()
    
    df = df.astype('str')

    print(df)
    df.to_parquet('D:\\test\\myfile.parquet')

While running, i m getting error:

File: 'pandas\_libs\tslibs\timezones.pyx', line 284 in pandas.libs.tslibs.timezones.get_dst_info
AttributeError: 'NoneType' object has no attribute 'total_seconds'

I know this error is related to date time, but i have no idea how to resolve this.