Python Errors and Exceptions

Errors and Exceptions are mechanisms used to handle unexpected or erroneous situations that may occur during program execution. When a Python script encounters an error or exception, it can disrupt the normal flow of the program and cause it to terminate prematurely. To avoid abrupt terminations and provide more informative feedback to developers, Python provides ways to catch and handle these errors and exceptions. Here are some essential details about Python Errors and Exceptions:

Syntax Errors

Syntax errors occur when the Python interpreter detects a violation of the language's syntax rules. These errors prevent the script from being executed altogether and are typically identified during the parsing phase before the code is executed.


Exceptions are errors that occur during the execution of a program. They can be caused by various reasons, such as incorrect user input, accessing non-existing variables, or dividing by zero. When an exception occurs, the program halts, and Python raises an exception object.

Exception Handling

Python allows developers to handle exceptions using the try, except, else, and finally blocks. The try block encloses the code that may raise an exception. If an exception occurs within the try block, the corresponding except block is executed, and the program continues running. The else block is executed if no exceptions occur in the try block. The finally block is used to specify code that must be executed regardless of whether an exception was raised or not.

Python Errors

Catching Specific Exceptions

Developers can specify the type of exception to catch using specific exception classes after the except keyword. This allows for more fine-grained handling of different types of errors.

Exception Hierarchy

Python has a hierarchy of exception classes, with the base class being BaseException. All built-in exceptions inherit from this base class. Common exception classes include TypeError, ValueError, ZeroDivisionError, FileNotFoundError, and IndexError, among others.

Python logical errors

Raising Exceptions

Developers can manually raise exceptions using the raise keyword. This is useful when a specific condition is met, and the code needs to indicate an error.

Custom Exceptions

Developers can create custom exception classes by subclassing the built-in Exception class or any of its subclasses. This allows for creating custom error types that suit the needs of the application.


Errors and exceptions are an important part of Python programming. By understanding how errors and exceptions work, you can write more robust and reliable code.