I was starting a React Native project on my MacBook Air but when running the command:

npx react-native start

I got an error that contained this line:

Error: EMFILE: too many open files, watch

I tried various ways to solve, until I found the suggestion to install the watchman utility using Homebrew.

I ran

brew install watchman

and that fixed the problem, because React Native internally was able to use watchman to watch files changes (used to provide hot reloading in the app to refresh it when a file is changed).

watchman looks like it’s more efficient than the built-in files watch system, since I got rid of that error.