您错误地设置了 distFolder 变量.server.ts 中的 distFolder 必须指向包含客户端应用程序的文件，即应用程序中的 dist\YourProjectName\browser.请注意，这是在 angular.json 文件中配置的.

要纠正错误，请尝试更改 server.ts

中的 distFolder 路径

const distFolder = join(process.cwd(), 'dist','YourProjectName', 'browser');

So, I've been trying for days to get a angular universal app running but I keep getting this issue when I try to run the server like

npm run dev:s-s-r

I have set my server.ts file as in the below link https://github.com/Angular-RU/angular-universal-starter/blob/master/server.ts

My server.ts file is as below

import 'zone.js/dist/zone-node';

import { ngExpressEngine } from '@nguniversal/express-engine';
import * as express from 'express';
import { join } from 'path';

import { AppServerModule } from './src/main.server';
import { APP_BASE_HREF } from '@angular/common';
import { existsSync } from 'fs';

// s-s-r DOM
const domino = require('domino');
const fs = require('fs');
const path = require('path');
// index from browser build!
const template = fs.readFileSync(path.join('.', 'dist', 'index.html')).toString();
// for mock global window by domino
const win = domino.createWindow(template);
// from server build
const files = fs.readdirSync(`${process.cwd()}/dist-server`);
// mock
global['window'] = win;
// not implemented property and functions
Object.defineProperty(win.document.body.style, 'transform', {
  value: () => {
    return {
      enumerable: true,
      configurable: true,
    };
  },
});
// mock documnet
global['document'] = win.document;
// othres mock
global['CSS'] = null;
// global['XMLHttpRequest'] = require('xmlhttprequest').XMLHttpRequest;
global['Prism'] = null;

// The Express app is exported so that it can be used by serverless Functions.
export function app() {
  const server = express();
  const distFolder = join(process.cwd(), 'dist');
  const indexHtml = existsSync(join(distFolder, 'index.original.html')) ? 'index.original.html' : 'index';

  // Our Universal express-engine (found @ https://github.com/angular/universal/tree/master/modules/express-engine)
  server.engine('html', ngExpressEngine({
    bootstrap: AppServerModule,
  }));

  server.set('view engine', 'html');
  server.set('views', distFolder);

  // Example Express Rest API endpoints
  // server.get('/api/**', (req, res) => { });
  // Serve static files from /browser
  server.get('*.*', express.static(distFolder, {
    maxAge: '1y'
  }));

  // All regular routes use the Universal engine
  server.get('*', (req, res) => {
    res.render(indexHtml, { req, providers: [{ provide: APP_BASE_HREF, useValue: req.baseUrl }] });
  });

  return server;
}

function run() {
  const port = process.env.PORT || 4000;

  // Start up the Node server
  const server = app();
  server.listen(port, () => {
    console.log(`Node Express server listening on http://localhost:${port}`);
  });
}

// Webpack will replace 'require' with '__webpack_require__'
// '__non_webpack_require__' is a proxy to Node 'require'
// The below code is to ensure that the server is run only when not requiring the bundle.
declare const __non_webpack_require__: NodeRequire;
const mainModule = __non_webpack_require__.main;
const moduleFilename = mainModule && mainModule.filename || '';
if (moduleFilename === __filename || moduleFilename.includes('iisnode')) {
  run();
}

export * from './src/main.server';

my app.server.module.ts file:

import { NgModule } from '@angular/core';
import { ServerModule } from '@angular/platform-server';

import { AppModule } from './app.module';
import { AppComponent } from './app.component';

@NgModule({
  imports: [
    AppModule,
    ServerModule,
  ],
  bootstrap: [AppComponent],
})
export class AppServerModule {}

I am using Angular 9 and at a stage where I am thinking of dropping the idea of using angular universal at all. Seems it its way too unstable to be used at the moment.

Contents of dist folder:

Does anyone here have a solution to this?

You incorrectly set the distFolder variable. The distFolder from server.ts must point to the files containing the client side app, which is dist\YourProjectName\browser in your app. Note that this configured in angular.json file.

To correct your error, try changing the distFolder path in your server.ts

const distFolder = join(process.cwd(), 'dist','YourProjectName',  'browser');