Raising Exceptions in Python

Error Handling

Raising Exceptions the Right Way

Use built-in exception types—or create custom ones—to provide meaningful errors.

Raise with contextChain exceptions

Syntax

if not user.active:
    raise PermissionError("User is inactive")

• Include actionable, user-friendly messages.
• Attach metadata (e.g., offending IDs) for debugging.

Exception chaining

try:
    payload = json.loads(raw)
except json.JSONDecodeError as exc:
    raise ValueError("Invalid payload format") from exc

from exc preserves the original traceback, making debugging easier.

Next up in your learning path

Custom exceptions

Model domain errors with subclasses.

Architecture

Stack traces

Read tracebacks to diagnose root causes.

Debugging

Common error reference

Look up fixes for frequent Python errors.

Reference