Metro Builder: SyntaxError: Unexpected token = after upgrading to React Native 0.65.1

Question

Today I updated to React Native Version 0.65.1. After that I was unable to Start the Metro Server

I am now receiving following error message while building a Release .apk:

    node_modules/metro/src/Server.js:350
  processRequest = (req, res, next) => {
                 ^

SyntaxError: Unexpected token =
    at new Script (vm.js:80:7)
    at createScript (vm.js:274:10)
    at Object.runInThisContext (vm.js:326:10)
    at Module._compile (internal/modules/cjs/loader.js:664:28)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:712:10)
    at Module.load (internal/modules/cjs/loader.js:600:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:539:12)
    at Function.Module._load (internal/modules/cjs/loader.js:531:3)
    at Module.require (internal/modules/cjs/loader.js:637:17)
    at require (internal/modules/cjs/helpers.js:22:18)
info Run CLI with --verbose flag for more details.

> Task :app:bundleReleaseJsAndAssets FAILED

I've tried:

• Updating Node
• Cleaning Project
• Restarting Computer

This is the snippet from the Metro Server Node Module

processRequest = (req, res, next) => {
    this._processRequest(req, res, next).catch(next);
  };

Additional Information: I am using a MacBook Pro with macOS Big Sur 11.5.2

Thanks everyone

Answer 1

Just my two cents: I had the same problem. My problem was due to NVM. I used node version 14 for the current project but my default version was node 10. And metro server opened in a new terminal that didn't use the current node but the default one. Fixed it by setting node version to 14.

Fix: nvm alias default v14.17.0

Answer 2

I have used react native 0.66 after i downgraded into 0.64, this worked for me.

1. downgrade react into 0.64.0
2. clear node cache & gradle clean
3. npm install

Answer 3

I have a new React Native project on v0.66 and have encountered this but was able to fix it without downgrading.

So, I use nvm to manage my node versions and I'm on v16.13.0 currently, which should be ok, but it seems I also had node and yarn installed through brew. The node version in brew was v13.10.1.

To fix this:

1. Uninstall node and yarn from brew

brew uninstall yarn

brew uninstall node

2. Reinstall yarn globally through npm

npm install --global yarn

and it works 👍 hopefully this helps someone else

Answer 4

I am also using React Native latest version

"react": "17.0.2", "react-native": "0.66.2"

The problem in my system was the node version i was using node@10 and just using nvm i used default node version as node@14, which worked for me.

nvm use 14