Solve Python TypeError: 'bool' object is not iterable

Python TypeError: 'bool' object is not iterable message means a Boolean object (True or False) is being used in a context where an iterable object (like a list or tuple) is expected.

To solve this error, you need to correct the line where you iterate over a bool object.

An iterable object is an object that can be looped over, such as a list, tuple, or string.

In contrast, a Boolean object is a single value and cannot be looped over. Consider the code below:

x = True

for value in x:  # ❗️

The for loop in the code above tries to loop over the x variable, which is a Boolean.

This causes the following error:

Traceback (most recent call last):
  File ...
    for value in x:
TypeError: 'bool' object is not iterable

To avoid the error above, you need to pass an iterable object such as a list, a string, or a tuple to the for statement:

x = ["apple", "orange"] 

for value in x:

# apple
# orange   

One common cause of this error is when you reassign your variable value after it has been created.

In the following example, the x variable is first initialized as a list, but got reassigned as Boolean down the line:

# x initialized as a list
x = [1, 2, 3]

# x reassigned as a boolean
x = True

When you use the x variable after the x = True line, then you will get the 'bool' object is not iterable error.

Another common scenario where this error occurs is when you pass a Boolean object to a function that requires an iterable.

For example, the list(), tuple(), set(), and dict() functions all require an iterable to be passed:

x = True

# ❌ TypeError: 'bool' object is not iterable

You can also add an if statement to check if your variable is a boolean:

x = True

if type(x) == bool:
    print("x is of type Boolean.")  # ✅
    print("x is not of type Boolean.")

Or you can also use the isinstance() function to check if x is an instance of the bool class:

x = True

if isinstance(x, bool):
    print("x is of type Boolean.")  # ✅
    print("x is not of type Boolean.")

When you see a variable identified as a Boolean, you need to inspect your code and make sure that the variable is not re-assigned as Boolean after it has been declared.

You will avoid this error as long as you don’t pass a Boolean object where an iterable is expected.

Level up your programming skills

I'm sending out an occasional email with the latest programming tutorials. Drop your email in the box below and I'll send new stuff straight into your inbox!

No spam. Unsubscribe anytime.