I am working on creating a sample application of vue.js referring to the article of, but it is displayed as Your application is running here: http: // localhost: 8080 at npm start and it is not displayed even if accessed

Error message
This page is not working
If this happens repeatedly, contact the site owner.
Applicable source code


module.exports = {
  dev: {
    // Paths
    assetsSubDirectory: 'static',
    assetsPublicPath: '/',
    proxyTable: {},
    // Various Dev Server settings
    host: 'localhost', // can be overwritten by process.env.HOST
    port: 8080, // can be overwritten by process.env.PORT, if port is in use, a free one will be determined
    autoOpenBrowser: false,
    errorOverlay: true,
    notifyOnErrors: true,
    poll: false, // https://webpack.js.org/configuration/dev-server/#devserver-watchoptions-

    / **
     * Source Maps
     * /
    // https://webpack.js.org/configuration/devtool/#development
    devtool: 'cheap-module-eval-source-map',
    // If i have problems debugging vue-files in devtools,
    // set this to false-it * may * help
    // https://vue-loader.vuejs.org/en/options.html#cachebusting
    cacheBusting: true,
    cssSourceMap: true

Checked with HTTP ERROR 431 and deleted the cache
I also changed the port number to 5000, but it did not change.

Supplemental information (FW/tool version etc.)

vue --version 2.9.6
node -version v12.14.1

  • Answer # 1

    Change the port to 3000 and try npm start again. I'm worried about what error message will be displayed.

  • Answer # 2

    If you look at the additional information, Node.js is used Looks like,
    It is said that the HTTP request header size of the Node.js server has been greatly reduced for vulnerability countermeasures.
    Talk about the maximum size of Node.js HTTP request header
    What about this cause?