Realm-Web warning: Include polyfill for crypto-browserify

[ayomide_wilfred]

While following the steps mentioned in the tutorial:

Build a full-stack Web App without creating a server using MongoDB’s Atlas...

Faced the following issue when trying to start the React.js Development server:

WARNING in ./node_modules/bson/dist/bson.browser.esm.js 2196:26-55
Module not found: Error: Can't resolve 'crypto' in '/Users/sourabh/Work/expengo/node_modules/bson/dist'

BREAKING CHANGE: webpack < 5 used to include polyfills for node.js core modules by default.
This is no longer the case. Verify if you need this module and configure a polyfill for it.

If you want to include a polyfill, you need to:
        - add a fallback 'resolve.fallback: { "crypto": require.resolve("crypto-browserify") }'
        - install 'crypto-browserify'
If you don't want to include a polyfill, you can use an empty module like this:
        resolve.fallback: { "crypto": false }

[SourabhBagrecha]

Hi @ayomide_wilfred, welcome to the community.
Thank you for pointing this out, since that console message is a warning and NOT an error it won’t break your React app, therefore you should be able to continue with the rest of the tutorial without any issues.
Just open the browser and visit localhost:3000 and you will be able to see all your components as expected.
However, if you want to resolve the issue stated in the warning, please follow the instructions mentioned in the following post:

Can't resolve 'crypto' in node_modules/bson/dist react

Hi @Subhash_Malireddy, I had the same issue and Iwas able to fix it. Intro: I was using realm-web 1.6, I updated to 1.7 and the issue still appearing. I basically did what the error message suggest, it doesn’t specify the file that you have to modify but looking around I’ve figured out that you need to add this line: fallback: { "crypto": require.resolve("crypto-browserify") }, Into the file ./node_modules/react-scripts/config/webpack.config.js (line 304 to be precise in the react-scripts v…

If you have any doubts, please feel free to reach out to us.

Thanks and Regards.
Sourabh Bagrecha,
MongoDB