rt.toLowerCase is not a function on fresh next js init

[AkipTsaqif]

Link to the code that reproduces this issue

https://github.com/AkipTsaqif/next-js-init-error

To Reproduce

1. do npx create-next-app@latest and follow the steps as usual
2. do npm run dev
3. next js runs but produces error on the terminal, saying rt.toLowerCase is not a function at \node_modules\next\dist\compiled\webpack\bundle5.js:30:274042

Current vs. Expected behavior

next js should not produces those error

Provide environment information

Operating System:
  Platform: win32
  Arch: x64
  Version: Windows 11 Pro
  Available memory (MB): 32704
  Available CPU cores: 6
Binaries:
  Node: 20.11.1
  npm: N/A
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 14.2.1 // Latest available version is detected (14.2.1).
  eslint-config-next: 14.2.1
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 5.4.5
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

App Router

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

based on this SO question, that just been asked recently, this happens on next js 14.2

[kobysysouvanh]

I am also having this issue on 14.2.1

[abdulkareemolumoh]

I am having same issues. I started exprencing it ever since i updated my nextjs to 14.2.1

[jovar-dev]

The same issue. NextJS 14.2.1

[Oelshehawi]

Managed to temp fix it by just going into the bundle5.js file and just replacing rt.toLowerCase() -> rt.toString().toLowerCase()

[madrosir]

The same issue. NextJS 14.2.1

[PolGubau]

I tried to downgrade to 14.0.4 but still happening

Edit by maintainer bot: Comment was automatically minimized because it was considered unhelpful. (If you think this was by mistake, let us know). Please only comment if it adds context to the issue. If you want to express that you have the same problem, use the upvote 👍 on the issue description or subscribe to the issue for updates. Thanks!

[timneutkens]

Hey everyone, I've had a look at the reproduction repository but I'm unable to trigger the same error. We tried both macOS, Windows, and Codesandbox but it doesn't trigger. It'd be helpful to get more information than "same issue" for this, to let people know you're running into the same issue you can use the GitHub 👍 feature. Posting "same issue" is not taken into account when sorting issues by how many people are running into them.

Is everyone that commented on this issue using Windows? Something else? Which version of Node.js? Tip: you can run next info to get this information.

[rawic]

Hi,
I am also experiencing this issue with the rt.toLowerCase is not a function error when running yarn dev in a project. Here’s the output from running next info in my environment, which might help in identifying any commonalities causing this problem:

Version: Windows 11 Pro Education
  Available memory (MB): 32702
  Available CPU cores: 16
Binaries:
  Node: 20.11.0
  npm: N/A
  Yarn: 1.22.17
  pnpm: N/A
Relevant Packages:
  next: 14.2.1 // Latest available version is detected (14.2.1).
  eslint-config-next: 14.2.1
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 5.4.3
Next.js Config:
  output: N/A
Done in 1.84s.

Additionally, I've found that rolling back to Next.js version 14.1.4 resolves this issue.

[husen1003]

I am also getting the same issue:

Operating System:
Platform: win32
Arch: x64
Version: Windows 10 Pro
Available memory (MB): 15973
Available CPU cores: 8
Binaries:
Node: 20.11.1
npm: N/A
Yarn: N/A
pnpm: 8.7.5
Relevant Packages:
next: 14.2.1 // Latest available version is detected (14.2.1).
eslint-config-next: 14.2.1
react: 18.2.0
react-dom: 18.2.0
typescript: 5.4.5
Next.js Config:
output: N/A

[Hugo-Delattre]

Additionally, I've found that rolling back to Next.js version 14.1.4 resolves this issue.

I had the same issue on latest version, I confirm that rolling back to Next.js 14.1.4 solved it (thanks Rawic!)

[alexanderwford]

I'm also having this issue

Operating System:
  Platform: win32
  Arch: x64
  Version: Windows 11 Pro
  Available memory (MB): 131017
  Available CPU cores: 16
Binaries:
  Node: 21.6.2
  npm: N/A
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 14.2.1 // Latest available version is detected (14.2.1).
  eslint-config-next: 13.5.6
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 5.4.5
Next.js Config:
  output: N/A

[Poylar]

Operating System:
  Platform: win32
  Arch: x64
  Version: Windows 10 Pro
  Available memory (MB): 16307
  Available CPU cores: 16
Binaries:
  Node: 20.9.0
  npm: N/A
  Yarn: N/A
  pnpm: 8.15.5
Relevant Packages:
  next: 14.2.1 // Latest available version is detected (14.2.1).
  eslint-config-next: 14.2.1
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 5.4.4
Next.js Config

downgrade to 14.1.2 not fixed the problem, only 14.0.2 fixed

[alexanderwford]

Disabling the Console Ninja VS Code Extension fixed this for me.