Document Fast Refresh requirements and troubleshooting

Bug report

Describe the bug

Fast refresh is not working when using named exports alongside default export.

To Reproduce

• Setup new next project using next init
• Go to pages/index.js and remove export default from your function component

export default function Home() {...}
// to
function Home() {...}

• export something alongside your component as default

// end of the file
let a = 2;
export { a, Home as default};

Expected behavior

Fast refresh should work

System information

• OS: Linux
• Browser Chromium latest
• Version of Next.js: 9.4.1
• Version of Node.js: 12.16.3

[thadwoodman]

Can you elaborate why you’d like to do this?

@Timer sure! I’m trying to troubleshoot an error I’m getting on worker in my local dev environment:

Uncaught ReferenceError: $RefreshSig$ is not defined

After some Googling it seems like this is related to React Refresh and I only started seeing this error after upgrading to Next.js 9.4. I should note that there are other people on my team using the same build and not getting this error.

I was just looking for an easy way to turn off Fast Refresh to troubleshoot the issue.

[dohomi]

I’d like to know the reason of it too. I’m using TypeScript and exporting types in my components and not sure if that triggers a hard refresh? And how about to work with external libraries which export named components not default exports?