TypeError: 'X' object is not callable

What this error means

You put () after something that isn't a function. Python tried to call the value — like invoking a function — but the value is an int, list, str, or some other non-callable object. The most common cause is shadowing a built-in: you assigned a value to a name like list, int, str, or sum, and then later tried to use that built-in as a function.

When you see it

Traceback (most recent call last):
  File "main.py", line 3, in <module>
    n = int("42")
TypeError: 'int' object is not callable

Traceback (most recent call last):
  File "main.py", line 5, in <module>
    print(total())
TypeError: 'int' object is not callable

Why it happens

Three usual suspects:

1. You shadowed a built-in. Earlier code did int = 5 or list = [1, 2], so int(...) and list(...) now refer to your value, not the built-in function.
2. You added stray parentheses. You wrote result() when result is already the value, not a function returning the value.
3. You named a variable the same as a function in the same scope, so the function got overwritten.

int = 5                # shadowed the built-in
n = int("42")          # TypeError: 'int' object is not callable

total = sum([1, 2, 3])
print(total())         # total is 6, not a function

How to fix it

Stop using built-in names as variables. Rename your variable:

count = 5              # not `int = 5`
items = [1, 2, 3]      # not `list = [1, 2, 3]`
total = 6              # don't shadow `sum`

If you've already shadowed a built-in inside the REPL or a Jupyter notebook, recover it:

del int                # restores the built-in
# or
import builtins
n = builtins.int("42")

Drop the extra parentheses if the value isn't a function:

total = sum([1, 2, 3])
print(total)           # not total()

Watch out for class instances without __call__. Calling an instance like obj() only works if the class defines __call__. Use obj.method() to call a method instead.

When you'd actually see this in real code

• You imported from datetime import datetime and then wrote datetime = datetime.now(), blowing away the class.
• A loop variable list overwrote the built-in inside a comprehension.
• You assigned df = df.head (forgetting the parentheses) and then called df() later.
• A library's API was renamed: requests.session is the class, requests.Session() is how to instantiate it.

Related errors

• NameError: name 'X' is not defined — the opposite kind of name mistake.
• AttributeError: 'list' object has no attribute 'X' — calling methods that don't exist.
• AttributeError: module 'X' has no attribute 'Y'

See Also

• All Python errors — the full index, by type and by when it happens.
• Functions (tutorial)
• Naming conventions cheat sheet
• Classes (tutorial)