How to Fix Any Bug

Dan Abramov · 21 Oct 2025

Dan Abramov did not write this page.

Every claim below was made in this piece, quoted word for word and numbered in the order the piece makes them, so you can read it there rather than take our word for it. The sentence above each quote is our reading of the claim, not their wording. Each quote was checked against a stored copy of the page at build time; where the two differ, the quote is the fact.

Our reading
When narrowing a bug reproduction case, it should still be possible to obtain a passing result with the new case, not just a failing one.

Their wordsThis is why, whenever you narrow a repro, you should also confirm that a positive result ("everything works") is still possible to obtain with the new repro.
Our reading
Removing parts of the code one at a time while confirming the bug still reproduces is the most effective way to find a root cause once other theories are exhausted.

Their wordsI don't know any other method that's so effective after you've run out of theories.

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