Fix “npm ERR! ERESOLVE could not resolve” in Cloudflare Pages Build

If you’re deploying a React app (or any Node.js project) on Cloudflare Pages and encountering this common build error:

npm ERR! ERESOLVE could not resolve
npm ERR! While resolving: @date-io/date-fns@3.2.1
npm ERR! Found: date-fns@2.30.0
...
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force or --legacy-peer-deps

It means there's a peer dependency conflict between your packages

Problem

Cloudflare Pages currently does not allow you to edit the npm install command directly in the UI — it uses npm clean-install internally, and there's no UI field to pass --legacy-peer-deps.

The Fix

To bypass these dependency resolution issues, use the legacy behavior of npm by creating a .npmrc file in your project root with the following line:

legacy-peer-deps=true

Optional: Pin Node Version

You may also want to pin your Node version to avoid unexpected version upgrades. Add a .nvmrc file:

18.20.2

Cloudflare reads your .npmrc and .nvmrc files before the build starts. By setting legacy-peer-deps=true, it tells npm to skip peer dependency conflicts resolves the error during the install step.