angular/angular-cli · error

Invalid package.json, builders key not found.

Error message

Invalid package.json, builders key not found.

What it means

TestingArchitectHost.addBuilderFromPackage() imports the package's package.json and expects a 'builders' key pointing at the builders definition file (like builders.json). If the key is absent the package cannot supply builders, so the host throws this error.

Source

Thrown at packages/angular_devkit/architect/testing/testing-architect-host.ts:42

  constructor(
    public workspaceRoot = '',
    public currentDirectory: string = workspaceRoot,
    private _backendHost: ArchitectHost | null = null,
  ) {}

  addBuilder(
    builderName: string,
    builder: Builder,
    description = 'Testing only builder.',
    optionSchema: json.schema.JsonSchema = { type: 'object' },
  ): void {
    this._builderImportMap.set(builderName, builder);
    this._builderMap.set(builderName, { builderName, description, optionSchema });
  }
  async addBuilderFromPackage(packageName: string): Promise<void> {
    const packageJson = await import(packageName + '/package.json');
    if (!('builders' in packageJson)) {
      throw new Error('Invalid package.json, builders key not found.');
    }

    if (!packageJson.name) {
      throw new Error('Invalid package name');
    }

    const builderJsonPath = packageName + '/' + packageJson['builders'];
    const builderJson = await import(builderJsonPath);
    const builders = builderJson['builders'];
    if (!builders) {
      throw new Error('Invalid builders.json, builders key not found.');
    }

    for (const builderName of Object.keys(builders)) {
      const b = builders[builderName];
      // TODO: remove this check as v1 is not supported anymore.
      if (!b.implementation) {
        continue;

View on GitHub (pinned to bb72145f9a)

Solutions

1. Verify the package's package.json contains "builders": "./builders.json" (or similar path).
2. Add a builders key and a valid builders.json if you own the package.
3. Check the package name for typos and confirm it is a builder (not schematic-only) package.

Example fix

// before (package.json)
{ "name": "@myorg/builders" }
// after
{ "name": "@myorg/builders", "builders": "./builders.json" }

const pkg = require(packageName + '/package.json');
if (!('builders' in pkg)) {
  throw new Error(`${packageName} does not export a builders key`);
}
await architectHost.addBuilderFromPackage(packageName);

function hasBuildersKey(pkg: object): pkg is { builders: string } {
  return 'builders' in pkg && typeof (pkg as any).builders === 'string';
}

try {
  await architectHost.addBuilderFromPackage(packageName);
} catch (e) {
  if (e.message.includes('builders key not found')) {
    throw new Error(`Package ${packageName} is not a builder package`);
  }
  throw e;
}

When it happens

Trigger: Calling architectHost.addBuilderFromPackage(packageName) where the package's package.json has no 'builders' field — e.g. passing an app-only package, a plain library, or a typo'd package name that resolves to the wrong package.

Common situations: Testing custom builders and accidentally pointing at the wrong package name; packages authored without a builders entry (older schematics-only packages); scoped name typos like '@myorg/builders' vs '@myorg/builders-x'.

Related errors

• Invalid package name
• Invalid builders.json, builders key not found.
• Package ${JSON.stringify(name)} was found but does not suppo
• No project name provided and no default project found in wor
• Package ${JSON.stringify(name)} was not found in package.jso

AI-assisted analysis of angular/angular-cli@bb72145f9a (2026-08-30). Data as JSON: /api/errors/e868817fe1b79d08. Report an issue: GitHub.