The "@angular-devkit/build-webpack:webpack-dev-server" build

Error message

The "@angular-devkit/build-webpack:webpack-dev-server" builder is deprecated as part of Angular's Webpack support deprecation. Use "@angular/build" instead.

What it means

The @angular-devkit/build-webpack:webpack-dev-server builder emits a deprecation warning on every execution because Angular is deprecating its Webpack-based builders. Users are directed to the new esbuild-based "@angular/build" package.

Source

Thrown at packages/angular_devkit/build_webpack/src/builders/webpack-dev-server/index.ts:133

              address: typeof address === 'string' ? address : address.address,
            };
          });

          // Teardown logic. Close the server when unsubscribed from.
          return () => {
            devServer.stopCallback(() => {});
            webpackCompiler.close(() => {});
          };
        }),
    ),
  );
}

const builder: Builder<WebpackDevServerBuilderSchema> = createBuilder<
  WebpackDevServerBuilderSchema,
  DevServerBuildOutput
>((options, context) => {
  context.logger.warn(
    'The "@angular-devkit/build-webpack:webpack-dev-server" builder is deprecated as part of Angular\'s Webpack support deprecation. ' +
      'Use "@angular/build" instead.',
  );

  const configPath = pathResolve(context.workspaceRoot, options.webpackConfig);

  return from(getWebpackConfig(configPath)).pipe(
    switchMap((config) => runWebpackDevServer(config, context)),
  );
});

export default builder;

View on GitHub (pinned to bb72145f9a)

Solutions

Migrate the dev-server target to the "@angular/build:dev-server" builder (application builder).
If a custom webpack config is still required, evaluate migrating the config into the new builder's supported options or plugins.
If migration is not yet possible, acknowledge/suppress the warning and plan migration, since Webpack support will be removed in a future major version.

Example fix

// before (angular.json)
"builder": "@angular-devkit/build-webpack:webpack-dev-server"
// after
"builder": "@angular/build:dev-server"

Defensive patterns

Strategy: validation

Validate before calling

const ng = require('./angular.json');
for (const [name, p] of Object.entries(ng.projects)) {
  for (const [t, target] of Object.entries(p.architect ?? p.targets ?? {})) {
    if (target.builder === '@angular-devkit/build-webpack:webpack-dev-server') {
      console.warn(`${name}:${t} uses a deprecated webpack dev-server builder; migrate to @angular/build:dev-server`);
    }
  }
}

Prevention

Run `ng update` on major versions to auto-migrate builders.
Prefer @angular/build (esbuild) for new dev-server targets.
Lint angular.json in CI for deprecated builder names.

When it happens

Trigger: Any invocation of a target using "builder": "@angular-devkit/build-webpack:webpack-dev-server" in angular.json; the warning is emitted unconditionally at the start of the builder function.

Common situations: Custom workspaces with hand-rolled webpack configs for dev serving; older enterprise setups that never migrated off webpack-based serving; third-party schematics still generating webpack dev-server targets.

Related errors

AI-assisted analysis of angular/angular-cli@bb72145f9a (2026-08-30). Data as JSON: /api/errors/af09acb7283a9532. Report an issue: GitHub.