UnicodeDecodeError: ‘charmap’ codec can’t decode byte X in position Y: character maps to

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Solved1.06K viewsJuly 20, 2023143 guessing

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Nilesh Raut July 19, 2023 0 Comments

143 guessing

I’m trying to get a Python 3 program to do some manipulations with a text file filled with information. However, when trying to read the file I get the following error:

Traceback (most recent call last):  
  File "SCRIPT LOCATION", line NUMBER, in <module>  
    text = file.read()
  File "C:\Python31\lib\encodings\cp1252.py", line 23, in decode  
    return codecs.charmap_decode(input,self.errors,decoding_table)[0]
UnicodeDecodeError: 'charmap' codec can't decode byte 0x90 in position 2907500: character maps to `<undefined>`

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Nilesh Raut Selected answer as best July 20, 2023

1 Answer

score 0 · Answer 1 · 2023-07-19T12:00:37+00:00

The error you encountered is a UnicodeDecodeError, and it occurs when Python tries to decode text data using an encoding that doesn’t support certain characters in the input. The most common reason for this error is that the file contains characters that are not compatible with the default encoding (usually ASCII or CP1252 on Windows).

To resolve this issue, you can try the following approaches:

Specify the Correct Encoding: If you know the correct encoding of the text file, you can specify it explicitly when opening the file. For example, if the file is encoded in UTF-8, you can open it like this:

with open('file.txt', encoding='utf-8') as file: text = file.read()

Replace ‘file.txt’ with the actual path to your text file, and ‘utf-8’ with the correct encoding if it’s different.

Use a More Permissive Encoding: If you’re not sure about the encoding of the file, you can try using a more permissive encoding, such as ‘utf-8’ or ‘latin-1’, to read the file. ‘latin-1’ is a single-byte encoding that can handle all possible 8-bit byte values.

with open('file.txt', encoding='latin-1') as file: text = file.read()

Ignore Errors: Another option is to ignore errors during decoding by specifying the ‘ignore’ error handling option. This will skip characters that can’t be decoded.

with open('file.txt', encoding='utf-8', errors='ignore') as file: text = file.read()

Please note that using ‘ignore’ may cause some information loss if there are non-decodable characters in the file.

Detect Encoding: If you’re unsure about the encoding and it’s not specified anywhere, you can use external libraries like chardet to automatically detect the encoding.

import chardet
with open('file.txt', 'rb') as file: raw_data = file.read() result = chardet.detect(raw_data) encoding = result['encoding']
with open('file.txt', encoding=encoding) as file: text = file.read()

The chardet library will analyze the byte data and attempt to guess the encoding.

Choose the appropriate method based on your understanding of the file’s encoding. If you’re still unsure, you can inspect the file content or consult the source from which you obtained the file to determine its encoding.