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:  # ❗️
    print(value)

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:
    print(value)

# 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
list(x)
tuple(x)
set(x)
dict(x)

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.")  # ✅
else:
    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.")  # ✅
else:
    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.