Angular can’t find a directive with `{{ PLACEHOLDER }}` export name. The export name is specified in the `exportAs` property of the directive decorator. This is common when using FormsModule or Material modules in templates, and you’ve forgotten to [import the corresponding modules](https://angular.io/guide/sharing-ngmodules).
Use the export name to trace the templates or modules using this export.
Ensure that all dependencies are [properly imported and declared in your NgModules](https://angular.io/guide/sharing-ngmodules). For example, if the export not found is `ngForm`, we need to import `FormsModule` and declare it in the list of imports in `*.module.ts` to resolve the error.
```typescript
import { FormsModule } from '@angular/forms';
@NgModule({
...
imports: [
FormsModule,
…
```
If you recently added an import, you may need to restart your server to see these changes.