Cannot read property 'toLowerCase' of undefined

[arnaudjnn]

What version of Next.js are you using?

10.0.5

What version of Node.js are you using?

v14.12.0

What browser are you using?

Chrome

What operating system are you using?

macOS

How are you deploying your application?

next dev

Describe the Bug

I'm using Next with i18n-routing.

Here is my next.config.

module.exports = {
  i18n: { 
    locales: ["fr", "en"], 
    defaultLocale: "fr"
  },
}

When I try a slug which contain the specific keywords 'development' I get the following error:

TypeError: Cannot read property 'toLowerCase' of undefined
    at /Users/arnaud/Documents/edflex/node_modules/next/dist/next-server/lib/i18n/normalize-locale-path.js:2:89
    at Array.some (<anonymous>)
    at normalizeLocalePath (/Users/arnaud/Documents/edflex/node_modules/next/dist/next-server/lib/i18n/normalize-locale-path.js:2:55)
    at stripNextDataPath (/Users/arnaud/Documents/edflex/node_modules/next/dist/next-server/server/next-server.js:85:700)
    at DevServer.renderToHTMLWithComponents (/Users/arnaud/Documents/edflex/node_modules/next/dist/next-server/server/next-server.js:87:35)
    at DevServer.renderToHTML (/Users/arnaud/Documents/edflex/node_modules/next/dist/next-server/server/next-server.js:133:934)
    at async DevServer.renderToHTML (/Users/arnaud/Documents/edflex/node_modules/next/dist/server/next-dev-server.js:34:578)
    at async DevServer.render (/Users/arnaud/Documents/edflex/node_modules/next/dist/next-server/server/next-server.js:72:236)
    at async Object.fn (/Users/arnaud/Documents/edflex/node_modules/next/dist/next-server/server/next-server.js:47:704)
    at async Router.execute (/Users/arnaud/Documents/edflex/node_modules/next/dist/next-server/server/router.js:23:67)
    at async DevServer.run (/Users/arnaud/Documents/edflex/node_modules/next/dist/next-server/server/next-server.js:66:1042)
    at async DevServer.handleRequest (/Users/arnaud/Documents/edflex/node_modules/next/dist/next-server/server/next-server.js:34:1081)

Expected Behavior

I need to use a slug with the keyword development inside.

To Reproduce

Start the app with next dev and try the other locale than the default white the keyword development inside the slug

[ijjk]

Hi, this was already fixed in #19901 which is available in the latest canary of Next.js v10.0.6-canary.7, please update and give it a try!

[balazsorban44]

This issue has been automatically locked due to no recent activity. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.