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ERROR TypeError
Python TypeError
Python Error
An operation is applied to an object of an inappropriate type.
Root Cause
Passing the wrong type to a function, trying to concatenate a string and an integer, or calling a non-callable object.
How to Fix
Check the types of your variables. Use type() or isinstance() to debug. Convert types explicitly: str(number), int(string).
Quick Summary
TypeError means an operation was applied to the wrong type. Check variable types with type(), use isinstance() for type checking, and convert explicitly with str(), int(), float().
Key Takeaways
Key Takeaways
- Check types: type(variable) or isinstance(variable, int)
- Convert explicitly: str(42), int('42'), float('3.14')
- Common cause: concatenating str + int, use f-strings instead: f'Value: {number}'
- Type hints (Python 3.5+) help catch TypeErrors at development time
Use Cases
When to use it
- Concatenating a string and an integer
- Passing None where a string is expected
- Calling a variable that is not a function
Watch out
Common Mistakes
- Using + to concatenate strings and numbers, use f-strings or str() conversion
- Not validating input types from external sources (APIs, user input)
FAQ
TypeError Python TypeError, Frequently Asked
How do I check if a variable is a specific type?
isinstance(variable, int) returns True if variable is an int. Use isinstance(variable, (int, float)) to check multiple types.
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