Cannot find module "popper.js" Angular 5 Visual Studio 2017 asp.net core - asp.net

Question

I updated my Angular's verision from 4 to 5. Below is the screenshot, I followed the instruction as per the link http://www.talkingdotnet.com/upgrade-angular-4-app-angular-5-visual-studio-2017/
package.json file
{
"name": "VotingWebsite",
"private": true,
"version": "0.0.0",
"scripts": {
"test": "karma start ClientApp/test/karma.conf.js"
},
"devDependencies": {
"#angular/animations": "5.2.1",
"#angular/common": "5.2.1",
"#angular/compiler": "5.2.1",
"#angular/compiler-cli": "5.2.1",
"#angular/core": "5.2.1",
"#angular/forms": "5.2.1",
"#angular/http": "5.2.1",
"#angular/platform-browser": "5.2.1",
"#angular/platform-browser-dynamic": "5.2.1",
"#angular/platform-server": "5.2.1",
"#angular/router": "5.2.1",
"#ngtools/webpack": "1.9.5",
"#types/chai": "4.1.1",
"#types/jasmine": "2.8.5",
"#types/webpack-env": "1.13.3",
"angular2-router-loader": "0.3.5",
"angular2-template-loader": "0.6.2",
"aspnet-prerendering": "^3.0.1",
"aspnet-webpack": "^2.0.1",
"awesome-typescript-loader": "3.4.1",
"popper.js": "^1.12.5",
"bootstrap": "4.0.0",
"chai": "4.1.2",
"css": "2.2.1",
"css-loader": "0.28.9",
"es6-shim": "0.35.3",
"event-source-polyfill": "0.0.12",
"expose-loader": "0.7.4",
"extract-text-webpack-plugin": "3.0.2",
"file-loader": "1.1.6",
"html-loader": "0.5.5",
"isomorphic-fetch": "2.2.1",
"jasmine-core": "2.9.1",
"jquery": "3.3.1",
"json-loader": "0.5.7",
"karma": "2.0.0",
"karma-chai": "0.1.0",
"karma-chrome-launcher": "2.2.0",
"karma-cli": "1.0.1",
"karma-jasmine": "1.1.1",
"karma-webpack": "2.0.9",
"preboot": "6.0.0-beta.1",
"raw-loader": "0.5.1",
"reflect-metadata": "0.1.12",
"rxjs": "5.5.6",
"style-loader": "0.19.1",
"to-string-loader": "1.1.5",
"typescript": "2.6.2",
"url-loader": "0.6.2",
"webpack": "3.10.0",
"webpack-hot-middleware": "2.21.0",
"webpack-merge": "4.1.1",
"zone.js": "0.8.20"
}
}
I am getting an error as
Uncaught Error: Cannot find module "popper.js"
at webpackMissingModule (vendor.js?v=g866IhqI_4JvgibiHgn9GiAXKfG42-s7C9LGGfxA0Tk:sourcemap:82252)
at vendor.js?v=g866IhqI_4JvgibiHgn9GiAXKfG42-s7C9LGGfxA0Tk:sourcemap:82252
at Object.<anonymous> (vendor.js?v=g866IhqI_4JvgibiHgn9GiAXKfG42-s7C9LGGfxA0Tk:sourcemap:82255)
at __webpack_require__ (vendor.js?v=g866IhqI_4JvgibiHgn9GiAXKfG42-s7C9LGGfxA0Tk:sourcemap:21)
at Object.<anonymous> (bootstrap.js from dll-reference vendor_19596f3f8868cecda14a:1)
at __webpack_require__ (bootstrap acba0f7e8b1985fd75ba:678)
at fn (bootstrap acba0f7e8b1985fd75ba:88)
at Object.<anonymous> (process-update.js:146)
at __webpack_require__ (bootstrap acba0f7e8b1985fd75ba:678)
at fn (bootstrap acba0f7e8b1985fd75ba:88)
Webpack.config.js
const path = require('path');
const webpack = require('webpack');
const merge = require('webpack-merge');
const AngularCompilerPlugin = require('#ngtools/webpack').AngularCompilerPlugin;
const CheckerPlugin = require('awesome-typescript-loader').CheckerPlugin;
module.exports = (env) => {
// Configuration in common to both client-side and server-side bundles
const isDevBuild = !(env && env.prod);
const sharedConfig = {
stats: { modules: false },
context: __dirname,
resolve: { extensions: [ '.js', '.ts' ] },
output: {
filename: '[name].js',
publicPath: 'dist/' // Webpack dev middleware, if enabled, handles requests for this URL prefix
},
module: {
rules: [
{ test: /\.ts$/, use: isDevBuild ? ['awesome-typescript-loader?silent=true', 'angular2-template-loader', 'angular2-router-loader'] : '#ngtools/webpack' },
{ test: /\.html$/, use: 'html-loader?minimize=false' },
{ test: /\.css$/, use: [ 'to-string-loader', isDevBuild ? 'css-loader' : 'css-loader?minimize' ] },
{ test: /\.(png|jpg|jpeg|gif|svg)$/, use: 'url-loader?limit=25000' }
]
},
plugins: [new CheckerPlugin()]
};
// Configuration for client-side bundle suitable for running in browsers
const clientBundleOutputDir = './wwwroot/dist';
const clientBundleConfig = merge(sharedConfig, {
entry: { 'main-client': './ClientApp/boot.browser.ts' },
output: { path: path.join(__dirname, clientBundleOutputDir) },
plugins: [
new webpack.DllReferencePlugin({
context: __dirname,
manifest: require('./wwwroot/dist/vendor-manifest.json')
})
].concat(isDevBuild ? [
// Plugins that apply in development builds only
new webpack.SourceMapDevToolPlugin({
filename: '[file].map', // Remove this line if you prefer inline source maps
moduleFilenameTemplate: path.relative(clientBundleOutputDir, '[resourcePath]') // Point sourcemap entries to the original file locations on disk
})
] : [
// Plugins that apply in production builds only
new webpack.optimize.UglifyJsPlugin(),
new AngularCompilerPlugin({
tsConfigPath: './tsconfig.json',
entryModule: path.join(__dirname, 'ClientApp/app/app.browser.module#AppModule'),
exclude: ['./**/*.server.ts']
})
])
});
// Configuration for server-side (prerendering) bundle suitable for running in Node
const serverBundleConfig = merge(sharedConfig, {
resolve: { mainFields: ['main'] },
entry: { 'main-server': './ClientApp/boot.server.ts' },
plugins: [
new webpack.DllReferencePlugin({
context: __dirname,
manifest: require('./ClientApp/dist/vendor-manifest.json'),
sourceType: 'commonjs2',
name: './vendor'
})
].concat(isDevBuild ? [] : [
// Plugins that apply in production builds only
new AngularCompilerPlugin({
tsConfigPath: './tsconfig.json',
entryModule: path.join(__dirname, 'ClientApp/app/app.server.module#AppModule'),
exclude: ['./**/*.browser.ts']
})
]),
output: {
libraryTarget: 'commonjs',
path: path.join(__dirname, './ClientApp/dist')
},
target: 'node',
devtool: 'inline-source-map'
});
return [clientBundleConfig, serverBundleConfig];
};
It was working perfectly with angular 4 template in asp.net core Visual Studio 2017. When I update the package to Angular 5, I'm getting an error as described above.
I tried to google the solution, but not able to find the solution.

Answer 1

I fixed the same problem in my project by:
1) Adding popper.js to the package.json file (I see you already have this), and running "npm install":
"popper.js": "^1.12.9",
2) Adding an Import popper.js statement to the boot.browser.js file before the import bootstrap statement:
import 'popper.js';
import 'bootstrap';

Answer 2

For newer versions of Angular, npm install #popperjs/core did the trick!

Answer 3

Probably you need to run npm install after you have updated your package.json file.