Puppeteer: Protocol error (Target.setDiscoverTargets): Target closed

Puppeteer talks to Chrome over the Chrome DevTools Protocol. During puppeteer.launch() or puppeteer.connect(), one of the first commands it sends is Target.setDiscoverTargets. If the browser connection closes before the reply arrives, every pending command is rejected with Target closed, and the method name in parentheses tells you which command was waiting.

When the method is Target.setDiscoverTargets, the browser died almost immediately after starting. That makes this a launch-environment problem in disguise: the same root causes as Failed to launch the browser process, but the process lived just long enough to open the connection. Containers with tiny /dev/shm, missing libraries, sandbox restrictions and out-of-memory kills are the usual culprits. With other method names, for example Runtime.callFunctionOn, the page or browser closed mid-script.

What is not wrong: your scraping logic. No page has loaded yet.

const browser = await puppeteer.launch({
  dumpio: true, // pipe Chrome's stdout/stderr to the console
  args: ['--disable-dev-shm-usage'],
});

# docker run with more shared memory
docker run --shm-size=1gb my-scraper

Size containers for Chrome: at least 1 GB of shared memory or --disable-dev-shm-usage, and enough RAM for the number of concurrent pages. Keep a launch smoke test in CI. When the method in parentheses is not a Target command, look for code that closes the browser too early.