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Python › Debugging & Profiling

How do you use the built-in pdb debugger to pause execution at a specific line?

Beginner

Answer

Insert 'import pdb; pdb.set_trace()' (or the shorter 'breakpoint()' in Python 3.7+) at the line where you want execution to pause — this drops you into an interactive debugger prompt where you can inspect variables, step through code, and evaluate expressions.
def calculate_total(items):
    breakpoint()  # execution pauses here, drops into pdb
    return sum(item.price for item in items)
Real-world example Pausing mid-function to inspect why a calculated total doesn't match the expected value.

Common follow-ups: What are the basic pdb commands for stepping through code: 'n', 's', 'c', and 'l'?

Exception Handling
All 15 Debugging & Profiling questions