Pandas - 'Series' object has no attribute 'Columns'

Question

Tried to aggregate the values from the column C if the column A & B are null. I have tried the code, it was working fine for few tables and got a error for one of the table. Any Suggestions?

Code :

from tabula import read_pdf 
from tabulate import tabulate
from tabula import read_pdf
import pandas as pd
import numpy as np

# guess=False, pages=page,stream=True

Page_No = 45
tables = read_pdf('/content/210812154731_DECK CRANE - MACGREGOR HAGGLUND - TG 5795-36.5 130-2 - N00024-93-C-2220 - PARTS MANUAL.pdf',  pages=Page_No)
data_df = pd.DataFrame(tables[0])
# data_df['Dump'] = data_df.iloc[:,0:1]

out= data_df.ffill().groupby(['Item', 'SMR','CAGE','Part Number','Qty'], as_index=False)['Description'].agg(' '.join)

DATA:

   A        B       C
12525    1FWE23   1H654D
                  14654        
24798    14654    S56E82
65116    63546    38945        
46456    46485    R68R45
                  AD545    
A5D66    45346    QA6683       

EXPECTED:

   A        B       C
12525    1FWE23   1H654D 14654       
                   
24798    14654    S56E82
65116    63546    38945
46456    46485    R68R45 AD545    
                  
A5D66    45346    QA6683