Where does /undefined come from when running dev-server in webpack?

Question

webpack

Previously, everything was ok, the exact moment when it started to behave this way will not work, maybe it was updated, maybe it changed in the config.
In general, I run yarn dev, in the console:

yarn dev v0.24.6
$ webpack-dev-server --env development
Project is running at http://localhost:8080/
webpack output is served from /
Content not from webpack is served from c:\Mudrenok\dkv\dkv-frontend\build
404s will fallback to /index.html
webpack: wait until bundle finished: /undefined

webpack: Compiled successfully.

Everything seems to be ok, the only moment is what kind of "wait until bundle finished: / undefined"?
And in the browser, instead of the usual localhost:8080, it opens to me localhost:8080/undefined

Answer 1

There was the same bug, to be honest, I never got to the bottom of the reason, but there is a hotfix in the issue on the github:

devServer: {
    host: 'localhost',
    port: 3000,
    contentBase: './dist',
    hot: true,
    open: true,
    openPage: '', // <== Добавить вот это
  },