'utf-8' codec can't decode byte 0xb8 in position 77: invalid start byte

Question

With the help from these two questions I have coded a program to help me count words in csv files through given directories.

question no1: Counting elements in specified column of a .csv file

question no2: Sum of values from multiple dicts

When I pass a directory it kind of works like I want it to. Now I have stumbled across a problem. I pass a new directory. The file names are of the same pattern, I have tried moving to another disk, tried putting r' in front of the path etc. But I keep getting this error: 'utf-8' codec can't decode byte 0xb8 in position 77: invalid start byte

Here is the full code and the full error message.:

import numpy as np
import csv
import glob
import pandas as pd
import os
import collections
import functools
import operator
import matplotlib.pyplot as plt

root = input("Direktorij: ")
ext = ('.csv')

for subdir, dirs, files in os.walk(root):
seznam = [] #here i create an empty list to use in the next for loop.

for datoteka in os.scandir(subdir):
    if datoteka.path.endswith(ext):
        df = pd.read_csv(datoteka)
        klasifikacija = df.iloc[:, 4]  #this gets me all of the files from a directory with .csv extension
        napake = klasifikacija.value_counts() #this counts the same words
        dict_napake = dict(napake)
        seznam.append(dict_napake)
        napake = dict(functools.reduce(operator.add,map(collections.Counter, seznam)))
        
        
with open('petek.csv', 'a') as output:  #from here on the code is use to write the results in a new csv file. This kind of works as I want it to.
    writer = csv.writer(output)
    for key, value in napake.items():
        writer.writerow([key, value])    
    
indeks = subdir.split("\\")[-1]
with open('petek.csv', 'a') as output:
    writer = csv.writer(output)
    writer.writerow(indeks)    
print(f'{indeks} \n {napake}')



   print("done") #Makes it easier to know if the code ran to the end

Here is the error message:

UnicodeDecodeError                        Traceback (most recent call last)
Input In [40], in <cell line: 1>()
      4 for datoteka in os.scandir(subdir):
      5     if datoteka.path.endswith(ext):
----> 6         df = pd.read_csv(datoteka)
      7         klasifikacija = df.iloc[:, 4]  # Gets all rows for the fourth column (index starts at 0)
      8         napake = klasifikacija.value_counts()

File C:\ProgramData\Anaconda3\lib\site-packages\pandas\util\_decorators.py:311, in deprecate_nonkeyword_arguments.<locals>.decorate.<locals>.wrapper(*args, **kwargs)   
    305 if len(args) > num_allow_args:
    306     warnings.warn(
    307         msg.format(arguments=arguments),
    308         FutureWarning,
    309         stacklevel=stacklevel,
    310     )
--> 311 return func(*args, **kwargs)

File C:\ProgramData\Anaconda3\lib\site-packages\pandas\io\parsers\readers.py:680, in read_csv(filepath_or_buffer, sep, delimiter, header, names, index_col, usecols, squeeze, prefix, mangle_dupe_cols, dtype, engine, converters, true_values, false_values, skipinitialspace, skiprows, skipfooter, nrows, na_values, keep_default_na, na_filter, verbose, skip_blank_lines, parse_dates, infer_datetime_format, keep_date_col, date_parser, dayfirst, cache_dates, iterator, chunksize, compression, thousands, decimal, lineterminator, quotechar, quoting, doublequote, escapechar, comment, encoding, encoding_errors, dialect, error_bad_lines, warn_bad_lines, on_bad_lines, delim_whitespace, low_memory, memory_map, float_precision, storage_options)
    665 kwds_defaults = _refine_defaults_read(
    666     dialect,
    667     delimiter,
   (...)
    676     defaults={"delimiter": ","},
    677 )
    678 kwds.update(kwds_defaults)
--> 680 return _read(filepath_or_buffer, kwds)

File C:\ProgramData\Anaconda3\lib\site-packages\pandas\io\parsers\readers.py:575, in _read(filepath_or_buffer, kwds)
    572 _validate_names(kwds.get("names", None))
    574 # Create the parser.
--> 575 parser = TextFileReader(filepath_or_buffer, **kwds)
    577 if chunksize or iterator:
    578     return parser

File C:\ProgramData\Anaconda3\lib\site-packages\pandas\io\parsers\readers.py:933, in TextFileReader.__init__(self, f, engine, **kwds)
    930     self.options["has_index_names"] = kwds["has_index_names"]
    932 self.handles: IOHandles | None = None
--> 933 self._engine = self._make_engine(f, self.engine)

File C:\ProgramData\Anaconda3\lib\site-packages\pandas\io\parsers\readers.py:1235, in TextFileReader._make_engine(self, f, engine)
   1232     raise ValueError(msg)
   1234 try:
-> 1235     return mapping[engine](f, **self.options)
   1236 except Exception:
   1237     if self.handles is not None:

 File C:\ProgramData\Anaconda3\lib\site-packages\pandas\io\parsers\c_parser_wrapper.py:75, in CParserWrapper.__init__(self, src, **kwds)
     72     kwds.pop(key, None)
     74 kwds["dtype"] = ensure_dtype_objs(kwds.get("dtype", None))
---> 75 self._reader = parsers.TextReader(src, **kwds)
     77 self.unnamed_cols = self._reader.unnamed_cols
     79 # error: Cannot determine type of 'names'

File C:\ProgramData\Anaconda3\lib\site-packages\pandas\_libs\parsers.pyx:544, in pandas._libs.parsers.TextReader.__cinit__()

File C:\ProgramData\Anaconda3\lib\site-packages\pandas\_libs\parsers.pyx:633, in pandas._libs.parsers.TextReader._get_header()

File C:\ProgramData\Anaconda3\lib\site-packages\pandas\_libs\parsers.pyx:847, in pandas._libs.parsers.TextReader._tokenize_rows()

File C:\ProgramData\Anaconda3\lib\site-packages\pandas\_libs\parsers.pyx:1952, in pandas._libs.parsers.raise_parser_error()

UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb8 in position 77: invalid start byte