ESLint Exits 1 on Warnings - Fix --max-warnings 0 in CI

ESLint exits 0 when there are only warnings, so lint passes locally. CI commonly runs eslint --max-warnings 0, which makes any warning fail the job - so the same code that "passed" locally turns the pipeline red.

What this error means

CI fails on lint with exit 1 and a "too many warnings" summary, even though npx eslint . exits cleanly on your machine. The difference is the --max-warnings 0 flag in the CI command.

eslint

/app/src/App.tsx
  12:7  warning  'foo' is assigned a value but never used  @typescript-eslint/no-unused-vars

✖ 1 problem (0 errors, 1 warning)

ESLint found too many warnings (maximum: 0).

Common causes

CI treats warnings as failures

--max-warnings 0 makes ESLint exit 1 if any warning exists. Locally, without the flag, the same warnings are informational and ESLint exits 0.

Warning-level rules accumulating

Rules configured as warn (unused vars, exhaustive-deps) pile up over time. They are invisible until a --max-warnings gate turns them into a hard CI failure.

How to fix it

Reproduce the CI gate locally

Run lint with the same flag CI uses so you see the failure before pushing.

Terminal

npx eslint . --max-warnings 0
# fix each warning, or re-scope a rule to "off"/"error" deliberately

Clear or re-classify the warnings

Fix the underlying warnings (remove unused vars, add missing deps).
If a rule should not gate CI, set it to off; if it should, set it to error so intent is explicit.
Run --max-warnings 0 consistently so warning debt can never accumulate unseen.

How to prevent it

Run eslint --max-warnings 0 locally and in pre-commit, matching CI.
Decide each rule's severity deliberately - off or error, not lingering warn.
Keep the lint command identical across local and CI.