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What does the 'finally' block guarantee, and when is it typically used? How do you catch multiple exception types with a single except clause? Why is a bare 'except:' clause (catching everything with no type specified) generally discouraged? How do you create a custom exception class, and what's the minimal amount of code needed? How do you access details about the exception currently being handled, like its type, value, and traceback, using sys.exc_info()? How does the 'else' clause on a try statement work, and what's its purpose compared to just putting that code at the end of 'try'? How does Python 3.11's exception groups (ExceptionGroup) and the 'except*' syntax let you handle MULTIPLE unrelated exceptions raised together? How would you design a custom exception HIERARCHY for an application, and why does this matter for how callers can catch errors at different granularities? How does context manager __exit__ interact with exception handling, and how can it SUPPRESS an exception by returning True? How would you implement a retry-with-backoff decorator that catches specific transient exceptions and retries with increasing delays?
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Python › Exception Handling

What is the difference between 'raise' and 'raise ... from ...' for exception chaining?

Intermediate

Answer

Plain 'raise NewException()' inside an except block still shows BOTH the original and new exception in the traceback (implicit chaining, labeled 'During handling of the above exception...'); 'raise NewException() from original_exception' makes the chaining EXPLICIT, and 'raise NewException() from None' SUPPRESSES the original exception's context entirely, showing only the new one.
try:
    int("not a number")
except ValueError as e:
    raise RuntimeError("Failed to parse config") from e  # explicit chaining: shows both, labeled 'direct cause'

try:
    int("not a number")
except ValueError:
    raise RuntimeError("Failed to parse config") from None  # suppresses the ValueError entirely
Real-world example Wrapping a low-level parsing error in a more meaningful, higher-level exception while preserving (or intentionally hiding) the original cause.

Common follow-ups: When would you deliberately want to suppress the original exception's context using 'from None'?

Debugging & Profiling
All 15 Exception Handling questions