.jsx extensions not working after upgrade

I recently upgraded Browserify from v10.2.4 to v12.0.1 and Babelify from v6.1.2 to v7.2.0

After the upgrade, when I run my build process I keep getting errors along the lines of:

[14:33:08] Error: Cannot find module './About' from '/Users/mherbst/Repos/data-validation-tool/src/client/components'
    at /Users/mherbst/Repos/data-validation-tool/node_modules/browserify/node_modules/resolve/lib/async.js:55:21
    at load (/Users/mherbst/Repos/data-validation-tool/node_modules/browserify/node_modules/resolve/lib/async.js:69:43)
    at onex (/Users/mherbst/Repos/data-validation-tool/node_modules/browserify/node_modules/resolve/lib/async.js:92:31)
    at /Users/mherbst/Repos/data-validation-tool/node_modules/browserify/node_modules/resolve/lib/async.js:22:47
    at FSReqWrap.oncomplete (fs.js:95:15)

My file structure looks like:

Example src/client/components/About.jsx

module.exports = React.createClass({...});

Example src/client/components/index.js

module.exports = {
  About: require('./About')
};

Example src/client/main.js

import {About, ...} from 'components';
...
...
...

This setup worked with the old version of Browserify. It breaks after the upgrade. Here is part of my build (Gulp pipeline): Part of src/gulpfile.js

var bundler = browserify({
  entries: ['client/main.js'],
  options: {
    debug: true,
    extensions: ['.jsx']
  },
  cache: {},
  packageCache: {}
});

bundler.transform(babelify, { presets: ["es2015", "react"] });

When I change Example src/client/components/index.js to

module.exports = {
  About: require('./About.jsx')
};

it works, which is what makes me think it’s a bug maybe. Is it, or did I miss something?

[jmm]

You overwrote extensions with [".jsx"]. You need .js in there too.

[jmm]

@MatthewHerbst Ok, great!