Javascript – How can I fix the error: "{ "message": "Cannot PUT /app-user", "error": "Not Found", "statusCode": 404 }" while making a POST request in Postman?

**Entity code **

   import { Entity, PrimaryGeneratedColumn, Column } from 'typeorm';

@Entity({ name: 'app_user' })
export class User {
  @PrimaryGeneratedColumn({ name: 'user_id' })
  userId: number;

  @Column({ name: 'username', type: 'varchar', length: 255, unique: true })
  username: string;

  @Column({ name: 'user_password', type: 'varchar', length: 255 })
  userPassword: string;

  @Column({ name: 'user_role', type: 'varchar', length: 50 })
  userRole: string;
}

app-service

import { MessageCount } from './entities/message-count';
import { DataSource } from 'typeorm';
import { User } from './entities/app-user';

const logger = new Logger('AppService');

@Injectable()
export class AppService {
constructor(private readonly db: DataSource) {}
async appendUser(user: User) {
  // Assuming you have necessary validation or additional logic
  return this.appendUserToDB(user).catch((err) => {
    // Retry in case of an error
    logger.error(err);
    return this.appendUserToDB(user);
  });
}

private appendUserToDB(user: User) {
  return this.db.getRepository(User)
      .save(user)
      .then(() => {
        logger.verbose('User added successfully.');
      });
  
}

getHello(): string {
  return 'Hello World!';
}
}

Controller.ts

import { AppService } from './app.service';
import { MessageCount } from './entities/message-count';
import { User } from './entities/app-user';

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

  @Get()
  getHello(): string {
    return this.appService.getHello();
  }
@Post('add-user') // Adjust the route as needed
  async addUser(@Body() user: User) {
    try {
      await this.appService.appendUser(user);
      return { message: 'User added successfully' };
    } catch (error) {
      return { message: 'Error adding user', error: error.message };
    }
  }

app-module.ts

import { AppController } from './app.controller';
import { AppService } from './app.service';
import { ConfigManager } from './app.config';
import { DataSource } from 'typeorm';

const appConfigMgr = new ConfigManager();
const appDataSource = new DataSource(appConfigMgr.getConfigObject().dbConfig);

@Module({
  imports: [],
  controllers: [AppController],
  providers: [
    AppService,
    { provide: ConfigManager, useValue: appConfigMgr },
    { provide: DataSource, useValue: appDataSource },
  ],
})
export class AppModule {}

When making a POST request in Postman:

http://localhost:3000/add-user

With Body request:
{
"username": "admin",
"userPassword": "admin",
"userRole": "admin"
}

I’m getting the issue as:

{
"statusCode": 404,
"message": "Cannot POST /add-user",
"error": "Not Found"
}

I get error this while making a POST request in Postman
How can I fix the error: