TypeError: Cannot read property 'map' of undefined at Server.generateRoutes

Bug report

Describe the bug

I’ve been using nextjs with typescript to build a web app (based off of the example at https://github.com/mui-org/material-ui/tree/master/examples/nextjs-with-typescript). However, when I deploy my app to an AWS elastic beanstalk instance, I get a strange error that breaks my app. next start does not run correctly. I cannot reproduce this locally, only when I deploy to AWS’s elastic beanstalk.

Stack trace:

> next start --port 8081

TypeError: Cannot read property 'map' of undefined
    at Server.generateRoutes (/var/app/current/node_modules/next/dist/next-server/server/next-server.js:257:36)
    at new Server (/var/app/current/node_modules/next/dist/next-server/server/next-server.js:81:49)
    at createServer (/var/app/current/node_modules/next/dist/server/next.js:2:133)
    at start (/var/app/current/node_modules/next/dist/server/lib/start-server.js:1:323)
    at nextStart (/var/app/current/node_modules/next/dist/cli/next-start.js:22:125)
    at commands.(anonymous function).then.exec (/var/app/current/node_modules/next/dist/bin/next:29:346)
    at process._tickCallback (internal/process/next_tick.js:68:7)
    at Function.Module.runMain (internal/modules/cjs/loader.js:834:11)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:623:3)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! test-website@1.0.0 start: `next start --port 8081`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the test-website@1.0.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

To Reproduce

Deploy nextjs app with typescript to elastic beanstalk instance

Expected behavior

The app should just run next start normally.

System information

• OS: Node.js running on 64bit Amazon Linux/4.12.0
• Version of Next.js: both 9.1.16 and 9.1.17

[timneutkens]

Please provide a full reproduction including all code. Just 2 files is not enough.

[timneutkens]

I will say one thing however, there’s a lot of issues I’ve been having with next.js and whenever I find the bug posted here the development team always seem to deny any issues.

We don’t deny issues. I’ve already spent over an hour on this particular issue without being able to reproduce as no reproduction was provided.

We ask for a reproduction so that we can add a test in our test suite to ensure it doesn’t happen again.

Eg in this case I’ve asked for a full reproduction 5 times and 1 time it was provided, tried to reproduce based on the steps provided and couldn’t reproduce so posted back. Didn’t hear back from anyone experiencing the issue since.

In this case, it’s not really a bug with next.js, but perhaps advising to clear the cache and rebuild would be more constructive than “Cannot reproduce. Next.js can do no wrong.”

Specifically “Next.js can do no wrong”

I’ve never said that, I’ve only asked for a reproduction so that we can actually solve the issue you’re experiencing.