next is not defined

[bradrisse]

I have an intermittent issue on Google App Engine on a standard environment. The displayed browser error is

An unexpected error has occurred.

The console error is:

main-e9fcf9c93d6d8ac0e441.js:formatted:406 ReferenceError: next is not defined
    at Object.Pmoa (index.js:formatted:3121)
    at l (webpack-1c5199ff66550d26e499.js:formatted:40)
    at Module.RNiq (index.js:formatted:3599)
    at l (webpack-1c5199ff66550d26e499.js:formatted:40)
    at index.js:formatted:6381
    at main-e9fcf9c93d6d8ac0e441.js:formatted:1018
    at e.value (main-e9fcf9c93d6d8ac0e441.js:formatted:1033)
    at U (main-e9fcf9c93d6d8ac0e441.js:formatted:208)
    at Array.map (<anonymous>)
    at Object.IKlv (main-e9fcf9c93d6d8ac0e441.js:formatted:210)
te @ main-e9fcf9c93d6d8ac0e441.js:formatted:406

The production build line main-e9fcf9c93d6d8ac0e441.js:formatted:406

    Pmoa: function(e, t) {
        e.exports = next
    },

Building nextjs in development mode leads to this line

/***/ "Pmoa":
/***/ (function(module, exports) {

module.exports = require("next");

Upon refresh the issue is resolved.

My thoughts are that nextjs is being loaded after this line due to a cache issue or something else. I've tried to run down the cause to no avail. Any help or direction would be greatly appreciated.

[jamesmosier]

I'm not sure anything would be cache related, but how are you installing Next on your Google App Engine instance? Just via npm install (or yarn install) in your directory with your package.json? Have you checked to ensure Next is not installed globally too?

[bradrisse]

This is how the application is installed on google app engine https://github.com/bradrisse/nextjs-9-gae-demo. I'm also using 9.4.1, will try the upgrade.

It's very difficult to replicate, essentially through using the application over time I will encounter it.

[meakyl]

We have the same issue with a classic Next app on Chrome and on production mode only (version 9.4.1)
After next build and node server.js with a custom express server.
After an CTRL+F5, if we navigate through the application we have this error then hit F5 and everything is ok. If I do a CTRL+F5 again, next navigation breaks with this error : "ReferenceError: next is not defined".
I can't make it break in dev mode though.

[jamesmosier]

It might be worth upgrading to the latest version of Next (9.5.2) just to be certain this issue wasn't fixed in a release since 9.4.1.

Aside from that, do you happen to have a repository you could share that reproduces this? It doesn't have to be the exact repo, but just one that recreate this issue.