Python - pdf to txt only return (CID:number)

Question

I have 5 pdf-files, which i want to be converted to txt-files. 3 of the files work fine. The other 2 only return (CID:number), f.e.:

(cid:47)(cid:57)(cid:3)(cid:69)(cid:72)

I wrote my code with pdfminer. Has anyone an idea how to fix this or adjust my code?

Btw.: The text is in german no CJK and i tried to convered the file on the page https://www.pdf2go.com and it worked.

Here is my code:

import sys
import io
from pdfminer.pdfparser import PDFParser
from pdfminer.pdfpage import PDFPage
from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.layout import LAParams
from pdfminer.converter import XMLConverter, HTMLConverter, TextConverter

# importieren Modul regex
import re
import os

filename = 'test.pdf'

page_start_input = 24
pages = list(range((page_start_input-1),500))

def pdfparser(data):
    fp = open(data, 'rb')
    resource_manager = PDFResourceManager()
    retstr = io.StringIO()
    codec = 'utf-8'
    pagenos = set(pages)
    laparams = LAParams()
    device = TextConverter(resource_manager, retstr, codec=codec, laparams=laparams)
    interpreter = PDFPageInterpreter(resource_manager, device)


    for page in PDFPage.get_pages(fp, pagenos):
        interpreter.process_page(page)
        data = retstr.getvalue()
    # print (data)

    file = open("test_out.txt", "w", encoding='utf-8')
    file.write(data)
    file.close()



pdfparser(filename)