No NgModule metadata found for 'AppModule' Error in Angular 5 server-side rendering with --env.prod

Question

I'm trying to upgrade an ASP.NET Core + Angular 4 SPA project from .NET Core 2.0.0/Angular4 to .NET Core 2.0.3/Angular5. I managed to get everything working properly except for the server-side rendering in a production environment, i/e when I publish the app:

An unhandled exception has occurred: No NgModule metadata found for 'AppModule'.
Error: No NgModule metadata found for 'AppModule'.

The issue only happens when both of these two conditions are met:

• Webpack builds the packages using the --env.prod switch

• The Index.cshtml view file contains the asp-prerender-module parameter, just like in the following example:

  <app asp-prerender-module="ClientApp/dist/main-server">Loading...</app>

If I remove the switch and/or the parameter, the problem disappears (together with SSR).

There's a bunch of other info I can give:

• It's not something related to IIS, it happens at Kestrel-level.
• It's not related to the web server machine because I can even reproduce it with locally by manually launching Webpack with the --end.prod switch right before a Debug or Release run.
• It doesn't seem to have anything to do with the source code, as I can reproduce it even with a single-component sample app with very basic AppModule files and trivial code.
• The project was running perfectly fine with .NET Core 2.0.0 and Angular 4.3.x.
• The only major thing I changed in the webpack.config.js file is replacing the AotPlugin with the new, Angular5-specific AngularCompilerPlugin provided by the @ngtools/webpack package: I think that might as well be the cause, as the --env.prod switch makes use of that AOT compiler instead of the JIT one. That, or something related to the .NET SpaServices package - maybe not on-par with the new Angular5 and/or the new AoT compiler?

Sadly, I can't revert to the former AotPlugin because it throws errors as well - which is perfectly understandable, as it's not meant to be used with Angular5.

Software Versions

• .NET Core 2.0.3
• Angular 5.0.2
• @ngtools/webpack 1.8.2 (also tried with 1.8.1 - same outcome)
• WebPack 2.6.1 (also tried with 2.5.6 - same outcome)

webpack.config.js

const path = require('path');
const webpack = require('webpack');
const merge = require('webpack-merge');
const AotPlugin = 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: /(?:\.ngfactory\.js|\.ngstyle\.js|\.ts)$/, include: /ClientApp/, use: isDevBuild ? ['awesome-typescript-loader?silent=true', 'angular2-template-loader'] : '@ngtools/webpack' },
                { test: /\.html$/, 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 AotPlugin({
                tsConfigPath: './tsconfig.json',
                entryModule: path.join(__dirname, 'ClientApp/app/app.module.browser#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 AotPlugin({
                tsConfigPath: './tsconfig.json',
                entryModule: path.join(__dirname, 'ClientApp/app/app.module.server#AppModule'),
                exclude: ['./**/*.browser.ts']
            })
        ]),
        output: {
            libraryTarget: 'commonjs',
            path: path.join(__dirname, './ClientApp/dist')
        },
        target: 'node',
        devtool: 'inline-source-map'
    });

    return [clientBundleConfig, serverBundleConfig];
};

Answer 1

The @ngtool/webpack configuration for Angular 5 is somewhat different form Angular 2/4. So, I've changed the webpack.config.js as following,

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$/, include: /ClientApp/, use: isDevBuild ? ['awesome-typescript-loader?silent=true', 'angular2-template-loader'] : '@ngtools/webpack' },
                { test: /\.html$/, 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' },
                {
                    test: /(?:\.ngfactory\.js|\.ngstyle\.js)$/,
                    loader: '@ngtools/webpack',
                    options: {
                        tsConfigPath: '/tsconfig.json',
                    }
                }
            ]
        },
        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.module.browser#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.module.server#AppModule'),
                exclude: ['./**/*.browser.ts']
            })
        ]),
        output: {
            libraryTarget: 'commonjs',
            path: path.join(__dirname, './ClientApp/dist')
        },
        target: 'node',
        devtool: 'inline-source-map'
    });

    return [clientBundleConfig, serverBundleConfig];
};

And here is my package.json file,

   {
  "dependencies": {
    "@angular/animations": "^5.0.2",
    "@angular/cdk": "^5.0.0-rc0",
    "@angular/cli": "^1.6.0-beta.2",
    "@angular/common": "^5.0.2",
    "@angular/compiler": "^5.0.2",
    "@angular/compiler-cli": "^5.0.2",
    "@angular/core": "^5.0.2",
    "@angular/forms": "^5.0.2",
    "@angular/http": "^5.0.2",
    "@angular/material": "^5.0.0-rc0",
    "@angular/platform-browser": "^5.0.2",
    "@angular/platform-browser-dynamic": "^5.0.2",
    "@angular/platform-server": "^5.0.2",
    "@angular/router": "^5.0.2",
    "@ngtools/webpack": "^1.8.3",
    "@types/webpack-env": "^1.13.2",
    "angular2-template-loader": "0.6.2",
    "aspnet-prerendering": "^3.0.1",
    "aspnet-webpack": "^2.0.1",
    "awesome-typescript-loader": "^3.4.0",
    "bootstrap": "3.3.7",
    "css": "2.2.1",
    "css-loader": "^0.28.7",
    "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": "^1.1.5",
    "html-loader": "^0.5.1",
    "isomorphic-fetch": "2.2.1",
    "jquery": "3.2.1",
    "json-loader": "^0.5.7",
    "preboot": "^5.1.7",
    "raw-loader": "0.5.1",
    "reflect-metadata": "0.1.10",
    "request": "^2.83.0",
    "rxjs": "^5.5.2",
    "style-loader": "^0.19.0",
    "to-string-loader": "1.1.5",
    "typescript": "^2.6.1",
    "url-loader": "^0.6.2",
    "webpack": "^3.8.1",
    "webpack-hot-middleware": "^2.20.0",
    "webpack-merge": "^4.1.1",
    "zone.js": "^0.8.18"
  },
  "devDependencies": {
    "@types/chai": "^4.0.5",
    "@types/jasmine": "^2.8.2",
    "@types/node": "^8.0.53",
    "chai": "^4.1.2",
    "jasmine-core": "2.8.0",
    "karma": "1.7.1",
    "karma-chai": "0.1.0",
    "karma-chrome-launcher": "2.2.0",
    "karma-cli": "1.0.1",
    "karma-jasmine": "1.1.0",
    "karma-webpack": "2.0.6"
  },
  "name": "aspnetcoreangularspa",
  "private": true,
  "scripts": {
    "test": "karma start ClientApp/test/karma.conf.js"
  },
  "version": "0.0.0"
}

If you still having problems running the solution, please have a look at this repository for a working solution.

Hope it helps :)

Answer 2

As others suggested, the temporary solution is to remove the SSR (Server Side Rendering). That means opening the Home/Index.cshtml file and change

<app asp-prerender-module="ClientApp/dist/main-server">Loading...</app>

to

<app>Loading...</app>

Answer 3

I found your Issue while searching for a solution to my problem described here: https://github.com/aspnet/JavaScriptServices/issues/1388 So i tried your webpack-config and also tried to run the app from the repository, but when i do "dotnet publish" and then run the app i get this error:

Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[0]
      An unhandled exception has occurred: No NgModule metadata found for 'AppModule'.
      Error: No NgModule metadata found for 'AppModule'.
    at NgModuleResolver.module.exports.NgModuleResolver.resolve