Python for pdf to add a watermark function

pip install PyPDF2

import os
from PyPDF2 import PdfFileReader as pr
from PyPDF2 import PdfFileWriter as pw


def write_watermark(watermark_pdf_path: str, target_pdf_path: str):
    result_pdf = pw()
    pdf_file_name = (target_pdf_path)
    f_target = open(target_pdf_path, 'rb')
    f_watermark = open(watermark_pdf_path, 'rb')
    target_pdf = pr(f_target)
    watermark_page = pr(f_watermark).getPage(0)
    for page in range(target_pdf.getNumPages()):
        try: # This try except paragraph is a bug that has been super troublesome for me to solve all day.
            target_pdf.getPage(page).mergePage(watermark_page)
            result_pdf.addPage(target_pdf.getPage(page))
        except Exception as e:
            result_pdf.addPage(watermark_page)
    if not ("output"):
        ("output")
    result_pdf.write(open("output/watermark added_" + pdf_file_name, 'wb'))
    f_target.close()
    f_watermark.close()


def folder_pdf_files(folder: str) -> list[str]:  # How many pdf files inside a folder
    file_list = []
    for a, b, c in (folder):
        if b == []:
            for filename in c:
                if filename[-3:].lower() == 'pdf':
                    file_path = (a, filename)
                    file_list.append(file_path)
    print(folder, ": with ", len(file_list), "A pdf file.")
    return file_list


def group_write_watermark(path_array: list[str], watermark_pdf_path: str):  # A group of pdf files to add a watermark
    for pdf_path in path_array:
        print(pdf_path, "Adding a watermark in...")
        write_watermark(watermark_pdf_path, pdf_path)
    print("Finish.")


if __name__ == '__main__':
    watermark_pdf_path = "Watermark file.pdf".
    folder_pdf = "Catalog"  # Directory of the pdf to be watermarked
    pdf_list = folder_pdf_files(folder_pdf)
    group_write_watermark(pdf_list, watermark_pdf_path)

//Error message
<ipython-input-1-4f7e1b354328> in <module>()
     14      (p)
     15 with open('D:\\Program Files\\', 'wb') as f:
---> 16     (f)

D:\Program Files (x86)\anaconda\lib\site-packages\PyPDF2\ in write(self, stream)
    499                 md5_hash = md5(key).digest()
    500                 key = md5_hash[:min(16, len(self._encrypt_key) + 5)]
--> 501             (stream, key)
    502             (b_("\nendobj\n"))
    503 

D:\Program Files (x86)\anaconda\lib\site-packages\PyPDF2\ in writeToStream(self, stream, encryption_key)
    547             (stream, encryption_key)
    548             (b_(" "))
--> 549             (stream, encryption_key)
    550             (b_("\n"))
    551         (b_(">>"))

D:\Program Files (x86)\anaconda\lib\site-packages\PyPDF2\ in writeToStream(self, stream, encryption_key)
    470 
    471     def writeToStream(self, stream, encryption_key):
--> 472         (b_(self))
    473 
    474     def readFromStream(stream, pdf):

D:\Program Files (x86)\anaconda\lib\site-packages\PyPDF2\ in b_(s)
    236             return s
    237         else:
--> 238             r = ('latin-1')
    239             if len(s) < 2:
    240                 bc[s] = r

UnicodeEncodeError: 'latin-1' codec can't encode characters in position 8-11: ordinal not in range(256)

try:
   return NameObject(('utf-8'))
   except (UnicodeEncodeError, UnicodeDecodeError) as e:
   # Name objects should represent irregular characters
   # with a '#' followed by the symbol's hex number
   if not :
      ("Illegal character in Name Object", )
      return NameObject(name)
   else:
      raise ("Illegal character in Name Object")

try:
     return NameObject(('utf-8'))
 except (UnicodeEncodeError, UnicodeDecodeError) as e:
     try:
         return NameObject(('gbk'))
     except (UnicodeEncodeError, UnicodeDecodeError) as e:
         # Name objects should represent irregular characters
         # with a '#' followed by the symbol's hex number
         if not :
             ("Illegal character in Name Object", )
             return NameObject(name)
         else:
             raise ("Illegal character in Name Object")

 r = ('latin-1')
 if len(s) < 2:
   		bc[s] = r
 return r

try:
    r = ('latin-1')
    if len(s) < 2:
        bc[s] = r
    return r
except Exception as e:
    print(s)
    r = ('utf-8')
    if len(s) < 2:
        bc[s] = r
    return r