Python typeerror: a bytes-like object is required, not ‘str’ Solution

TypeErrors happen all of the time in Python. This type of error is raised when you try to apply a function to a value that does not support that function. For example, trying to iterate over a number raises a TypeError because you cannot iterate over a number.

In this guide, we’re going to talk about how to solve the “typeerror: a bytes-like object is required, not ‘str’” error. We’ll walk through what this error means and why it is raised. We’ll also go through a solution to help you overcome this error. Let’s begin!

The Problem: typeerror: a bytes-like object is required, not ‘str’

Let’s start by analyzing our error message:

typeerror: a bytes-like object is required, not 'str'

This error message gives us two vital pieces of information. TypeError tells us that we’re applying a function to a value of the wrong type.

The error message tells us that we’re treating a value like a string rather than a bytes-like object. Bytes-like objects are objects that are stored using the bytes data type. Bytes-like objects are not strings and so they cannot be manipulated like a string.

A Practice Scenario

This error is commonly raised when you open a file as a binary file instead of as a text file.

There’s no better way to solve an error than to walk through an example of a code snippet with that error. Below is a program that replicates this error:

with open("recipes.txt", "rb") as file:
	recipes = file.readlines()

for r in recipes:
	if "Chocolate" in r:
		print(r)

This code snippet opens up the file “recipes.txt” and reads its contents into a variable called “recipes”.

The “recipes” variable stores an iterable object consisting of each line that is in the “recipes.txt” file. Next, we use a for loop to iterate over each recipe in the list.

In the for loop, we check if each line contains “Chocolate”. If a line contains the word “Chocolate”, that line is printed to the console. Otherwise, nothing happens.

Let’s run our code and see what happens:

Traceback (most recent call last):
  File "main.py", line 7, in <module>
	if "Chocolate" in r:
TypeError: a bytes-like object is required, not 'str'

An error has been raised!

The Solution

The error “a bytes-like object is required, not ‘str’” tells us that we’ve tried to access an object as if it were a string when we should be accessing it as if it were a list of bytes.

The cause of this error is that we’ve opened our file “recipes.txt” as a binary:

with open("recipes.txt", "rb") as file:

Binary files are not treated as lines of text. Instead, they are treated as a series of bytes. This means that when we try to check if “Chocolate” is in each line in the file, an error is raised. Python doesn’t know how to check for a string in a bytes object.

We can solve this error by opening our file in read mode instead of binary read mode:

with open("recipes.txt", "r") as file:

Read mode is used to read text files. Binary read mode is used to read binary files. We’ve removed the “b” from the mode parameter to read our file in read mode. Let’s try to run our code again:

Chocolate Fudge Cake
Chocolate Chip Cookie
Chocolate Square

Our code works! Now that our file is read using read mode, our code can perform an “if…in” comparison to check if “Chocolate” is in each line in the “recipes.txt” file.

Bytes-Like Object Similar Error

The error we have been discussing is similar to the error “TypeError: X first arg must be bytes or a tuple of bytes, not str”.

You may encounter this error if you try to use a string method on a list of bytes. To solve this error, you can use the same approach that we used to solve the last error. Make sure that you open up any text files in text read mode instead of binary read mode.

Conclusion

The error “typeerror: a bytes-like object is required, not ‘str’” is raised when you treat an object as a string instead of as a series of bytes. A common scenario in which this error is raised is when you read a text file as a binary.

Now you’re ready to solve the bytes-like object error like a Python pro!