Build-time prerendering not working anymore in Angular 19

[lucawalter]

Which @angular/* package(s) are the source of the bug?

core

Is this a regression?

Yes

Description

In Angular 18, I used SSG Build-time Prerendering by following this documentation: (https://angular.dev/guide/prerendering) I added a script to generate a routes.txt. The routes from the routes.txt have been prerendered without any problems. After updating to Angular 19, the build fails with following error message, although I did not change anything in my angular.json and also did not add a renderMode:

The ':uid' route uses prerendering and includes parameters, but 'getPrerenderParams' is missing. Please define 'getPrerenderParams' function for this route in your server routing configuration or specify a different 'renderMode'.

Isn't this way of prerendering not available anymore?

Please provide a link to a minimal reproduction of the bug

No response

Please provide the exception or error you saw

The ':uid' route uses prerendering and includes parameters, but 'getPrerenderParams' is missing. Please define 'getPrerenderParams' function for this route in your server routing configuration or specify a different 'renderMode'.

Please provide the environment you discovered this bug in (run ng version)

{
    "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
    "version": 1,
    "cli": {
        "packageManager": "yarn"
    },
    "newProjectRoot": "projects",
    "projects": {
        "dummy-project": {
            "projectType": "application",
            "schematics": {
                "@schematics/angular:component": {
                    "style": "scss",
                    "skipTests": true
                },
                "@schematics/angular:class": {
                    "skipTests": true
                },
                "@schematics/angular:directive": {
                    "skipTests": true
                },
                "@schematics/angular:guard": {
                    "skipTests": true
                },
                "@schematics/angular:interceptor": {
                    "skipTests": true
                },
                "@schematics/angular:pipe": {
                    "skipTests": true
                },
                "@schematics/angular:resolver": {
                    "skipTests": true
                },
                "@schematics/angular:service": {
                    "skipTests": true
                }
            },
            "root": "",
            "sourceRoot": "src",
            "prefix": "app",
            "architect": {
                "build": {
                    "builder": "@angular-devkit/build-angular:application",
                    "options": {
                        "outputPath": "dist/dummy-project",
                        "aot": true,
                        "index": "src/index.html",
                        "browser": "src/main.ts",
                        "polyfills": ["zone.js"],
                        "tsConfig": "tsconfig.app.json",
                        "inlineStyleLanguage": "scss",
                        "assets": ["src/favicon.ico", "src/assets"],
                        "styles": ["@angular/material/prebuilt-themes/azure-blue.css", "src/styles.scss"],
                        "scripts": [],
                        "stylePreprocessorOptions": {
                            "includePaths": ["src"],
                        },
                        "server": "src/main.server.ts",
                        "prerender": {
                            "routesFile": "routes.txt",
                            "discoverRoutes": true
                        },
                        "ssr": {
                            "entry": "server.ts"
                        }
                    },
                    "configurations": {
                        "production": {
                            "optimization": true,
                            "sourceMap": false,
                            "budgets": [
                                {
                                    "type": "initial",
                                    "maximumWarning": "500kb",
                                    "maximumError": "1mb"
                                },
                                {
                                    "type": "anyComponentStyle",
                                    "maximumWarning": "2kb",
                                    "maximumError": "4kb"
                                }
                            ],
                            "outputHashing": "all",
                            "fileReplacements": [
                                {
                                    "replace": "src/environments/environment.ts",
                                    "with": "src/environments/environment.prod.ts"
                                }
                            ],
                            "assets": ["src/assets", "src/.htaccess", "src/robots.txt"]
                        },
                        "development": {
                            "optimization": false,
                            "extractLicenses": false,
                            "sourceMap": true
                        }
                    },
                    "defaultConfiguration": "development"
                },
                "serve": {
                    "builder": "@angular-devkit/build-angular:dev-server",
                    "configurations": {
                        "production": {
                            "buildTarget": "dummy-project:build:production"
                        },
                        "development": {
                            "buildTarget": "dummy-project:build:development"
                        }
                    },
                    "defaultConfiguration": "development"
                },
                "extract-i18n": {
                    "builder": "@angular-devkit/build-angular:extract-i18n",
                    "options": {
                        "buildTarget": "dummy-project:build"
                    }
                },
                "test": {
                    "builder": "@angular-devkit/build-angular:karma",
                    "options": {
                        "polyfills": ["zone.js", "zone.js/testing"],
                        "tsConfig": "tsconfig.spec.json",
                        "inlineStyleLanguage": "scss",
                        "assets": ["src/favicon.ico", "src/assets"],
                        "styles": ["@angular/material/prebuilt-themes/azure-blue.css", "src/styles.scss"],
                        "scripts": []
                    }
                }
            }
        }
    }
}


"@angular/animations": "^19.0.0",
    "@angular/cdk": "18.2.2",
    "@angular/common": "^19.0.0",
    "@angular/compiler": "^19.0.0",
    "@angular/core": "^19.0.0",
    "@angular/forms": "^19.0.0",
    "@angular/platform-browser": "^19.0.0",
    "@angular/platform-browser-dynamic": "^19.0.0",
    "@angular/platform-server": "^19.0.0",
    "@angular/router": "^19.0.0",
    "@angular/ssr": "^19.0.1",

Anything else?

No response

[lucawalter]

In this documentation https://angular.dev/guide/prerendering , nobody explains that I have do define Server Routes. I just want to have the build-time Prerendering behaviour with txt. file

[alan-agius4]

Duplicate of #28948