Automated Migration Tools (ng update)

ng update is the Angular CLI’s built‑in command for updating projects and dependencies.
It not only updates package.json but also runs migration schematics that automatically transform your code to match the new version’s API.

How ng update Works

1. Dependency analysis – reads package.json and checks which packages have updates available.
2. Version compatibility – ensures that the requested update is possible (e.g., no conflicting peer dependencies).
3. Applying migrations – each package can provide a collection of schematics that are executed in order. These schematics modify source files, configuration, and dependencies.
4. Lock file update – after successful migrations, ng update updates package-lock.json or yarn.lock.

Running ng update

Update a single package (and its peer dependencies):

ng update @angular/core
Update multiple core packages together (recommended for Angular updates):

ng update @angular/core @angular/cli
See what updates are available:

ng update

Migration Schematics in Action

When you update from Angular 20 to 21, the @angular/core package may include schematics for:

New control flow migration – converts *ngIf/*ngFor to @if/@for.

Signal input migration – converts @Input() to input() where possible.

Remove @Injectable() provider migrations – simplifies provider declarations.

You can also run specific schematics independently, even without an update:

ng generate @angular/core:control-flow

Best Practices with ng update

Always commit your changes before running ng update, so you can revert if something goes wrong.

Run ng update one major version at a time. Skipping versions can cause migration scripts to fail.

Check the output – ng update often prints instructions for manual steps that cannot be automated.

After update, test thoroughly – run your unit tests, e2e tests, and manually verify critical paths.

Example Output of ng update

$ ng update @angular/core@21

Using package manager: npm
Collecting installed dependencies...
Found 42 dependencies.
Fetching dependency metadata from registry...
    Updating package.json with dependency @angular/core @ "21.0.0" (was "20.2.0")
    Updating package.json with dependency @angular/common @ "21.0.0" (was "20.2.0")
    Updating package.json with dependency @angular/compiler @ "21.0.0" (was "20.2.0")
    Updating package.json with dependency @angular/platform-browser @ "21.0.0" (was "20.2.0")
    Updating package.json with dependency @angular/platform-browser-dynamic @ "21.0.0" (was "20.2.0")
    Updating package.json with dependency @angular/router @ "21.0.0" (was "20.2.0")
    Updating package.json with dependency @angular/forms @ "21.0.0" (was "20.2.0")
    Updating package.json with dependency @angular/animations @ "21.0.0" (was "20.2.0")
    Updating package.json with dependency typescript @ "5.5.0" (was "5.4.0")
MIGRATION: Replace deprecated `@Injectable()` provider declarations.
  Successfully migrated 3 files.
MIGRATION: Convert `@Input()` to signal inputs.
  Successfully migrated 12 files.

ng update is the most powerful tool for keeping your Angular project up‑to‑date. Leverage it not only for Angular core packages but also for any library that provides migration schematics. Always read the migration logs and follow any manual instructions to ensure a smooth upgrade.