Puppeteer "Could not find Chromium" - Browser Not Downloaded in CI

Puppeteer looked for its Chromium build and the binary was not there. Either the download was skipped at install (an env var or puppeteer-core), or the cache directory does not match where Puppeteer searches.

What this error means

Launch fails with "Could not find Chromium (rev. NNNNNN). This can occur if either you did not perform an installation before running the script..." No browser is present to drive.

puppeteer

Error: Could not find Chromium (rev. 1108766). This can occur if either:
 1. you did not perform an installation before running the script
    (e.g. `npm install`) or
 2. your cache path is incorrectly configured.

Common causes

Download skipped at install

PUPPETEER_SKIP_DOWNLOAD/PUPPETEER_SKIP_CHROMIUM_DOWNLOAD was set, or puppeteer-core (which never downloads a browser) is used, so no Chromium was fetched.

Cache path mismatch

A custom PUPPETEER_CACHE_DIR at install time differs from runtime, or the CI cache was restored to a different path, so Puppeteer cannot find the build it expects.

How to fix it

Install the browser explicitly

Terminal

npx puppeteer browsers install chrome
# and unset any skip-download env var in CI

Pin a consistent cache dir

.npmrc

# .npmrc or CI env
PUPPETEER_CACHE_DIR=/home/runner/.cache/puppeteer

How to prevent it

Run puppeteer browsers install chrome after npm ci if downloads are skipped.
Set a stable PUPPETEER_CACHE_DIR for both install and run, and cache it.
Use puppeteer (not puppeteer-core) when you want a bundled browser.