Troubleshooting the "bytes-like object is required" Error in Python Requests

Feb 3, 2024 ยท 2 min read

When working with the popular Python Requests library for making HTTP requests, you may occasionally see this error:

"a bytes-like object is required, not 'str'"

This error occurs when Requests is expecting a bytes object but instead receives a str. Here are some common causes and solutions for this error:

Passing a String as File Data

If you are trying to upload a file using Requests, you need to pass file data as bytes:

with open('data.bin', 'rb') as f:
    files = {'file': f}
    r = requests.post(url, files=files) 

Note the 'rb' mode to open the file for reading bytes.

Passing Encoded Text as the Request Body

When sending text data like JSON in the request body, you need to first encode it to bytes:

data = json.dumps(some_dict)
r = requests.post(url, data=data.encode('utf-8'))

The .encode() method converts the string to bytes using the provided encoding.

Forgetting to Decode Response Content

If you try to access the response text property without calling .decode(), it will fail:

r = requests.get(url)
print(r.text) # may cause bytes-like object error

print(r.content.decode('utf-8')) # decode first

So remember to decode the raw response bytes to a string first.

Summary

  • Requests requires bytes for file uploads, request body encoding, and response content decoding.
  • Use 'rb' mode to read file data as bytes.
  • Encode text to bytes before sending.
  • Decode response content from bytes to strings before accessing.
  • Following these tips will help avoid the confusing "bytes-like object required" errors when using Requests.

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