Learn How to Fix TypeError in Python

How to Fix TypeError in Python

DodaTech Updated Jun 15, 2026 2 min read

Error message: TypeError: unsupported operand type(s) for +: 'int' and 'str'

Python raises TypeError when an operation or function is applied to an object of inappropriate type. It has several common variants.

Cause 1: Unsupported Operand Types

You’re mixing incompatible types in an operation:

# Wrong
result = "Hello" + 5  # TypeError!

# Fix — convert to matching types
result = "Hello" + str(5)  # "Hello5"
result = len("Hello") + 5  # 10

# Another example
count = 10
print("Count: " + count)  # TypeError: can only concatenate str (not "int") to str
# Fix
print("Count: " + str(count))  # "Count: 10"

Cause 2: Object Is Not Callable

You’re using parentheses () on something that isn’t a function:

# Wrong — integer is not callable
x = 42
print(x())  # TypeError: 'int' object is not callable

# Fix — remove parentheses
print(x)  # 42

# Another case — variable shadows function
sum = 10  # Overwrites built-in sum()
print(sum([1, 2, 3]))  # TypeError: 'int' object is not callable
# Fix — don't name variables after built-in functions
total = 10
print(sum([1, 2, 3]))  # 6

Cause 3: Cannot Unpack Non-Iterable

You’re trying to unpack a value that isn’t iterable:

# Wrong
a, b = 42  # TypeError: cannot unpack non-iterable int object

# Fix — make it iterable
a, b = (42, 0)

# Wrong — function returns single value, expecting tuple
def get_point():
    return 3  # Should return (x, y)

x, y = get_point()  # TypeError: cannot unpack non-iterable int object

# Fix — return a tuple
def get_point():
    return (3, 4)
x, y = get_point()  # OK

Cause 4: Missing Arguments

def greet(name, greeting):
    return f"{greeting}, {name}"

greet("Alice")  # TypeError: missing 1 required positional argument: 'greeting'
# Fix
greet("Alice", "Hello")

Prevention

Use type hints and run mypy to catch type mismatches early
Before operations, check types with isinstance()
Don’t shadow built-in names (sum, list, dict, str)
Convert types explicitly with str(), int(), float() when concatenating
Ensure functions return the expected number of values for unpacking

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