Error during WebSocket handshake: Unexpected response code: 200

[glekner]

• Operating System: WSL Fedora 31
• Node Version: 12.16.1
• NPM Version: 6.13.4
• webpack Version: 4.43.0
• webpack-dev-server Version: 3.11.0
• Browser: Chromium Edge 83

• This is a bug

After changing transportMode to ws im getting the following error in the console:

WebSocket connection to 'ws://localhost:9000/sockjs-node' failed: Error during WebSocket handshake: Unexpected response code: 200

My app is using a bridge, webpack-dev-server is on port 8080 and is only meant for compiling and hot-reloading.
I'm accessing the app from port 9000, where we have a bridge that uses the compiled assets with the help of writeToDisk.
Why am I getting this console error? isn't changing to transportMode to ws disable the usage of sockjs-node?
the app and websockets runs fine even though i'm getting it.

Code

  devServer: {
    writeToDisk: true,
    progress: true,
    hot: true,
    inline: true,
    contentBase: false,
    transportMode: 'ws',
  },

Expected Behavior

No error should show.

Actual Behavior

WebSocket connection to 'ws://localhost:9000/sockjs-node' failed: Error during WebSocket handshake: Unexpected response code: 200

For Bugs; How can we reproduce the behavior?

PR That causes this issue: openshift/console#5840

[alexander-akait]

Please create reproducible test repo, link on the issue is not reproducible test repo, I will reopen issue when you fill out For Bugs; How can we reproduce the behavior?