How to Fix DatabaseError in NestJS

If you've encountered a DatabaseError while working with NestJS, you're not alone. This is one of the most common issues developers face.

What Causes This Error

A DatabaseError typically means your application can't communicate with the database. Common causes include incorrect connection strings, connection pool exhaustion, missing migrations, or network issues between your app and the database server.

The Fix

The key is to set synchronize: false for production and configure retry attempts with connection pooling:

// app.module.ts
@Module({
  imports: [
    TypeOrmModule.forRoot({
      type: "postgres",
      url: process.env.DATABASE_URL,
      autoLoadEntities: true,
      synchronize: false, // Never true in production
      retryAttempts: 3,
      retryDelay: 3000,
      extra: { max: 10 },
    }),
  ],
})
export class AppModule {}

Common Pitfall

A common mistake is to ignore this error during development because it only surfaces under specific conditions. Always test with production-like settings to catch these issues early. If you're working in a team, document this fix in your project's troubleshooting guide so others don't hit the same wall.

Verify the Fix

After applying the fix, restart your NestJS application and verify the error no longer appears in the console or logs. Test both the happy path and edge cases to be thorough. If the error persists, double-check that your changes were saved and the application fully restarted.

Prevention

Tools like [Bugsly](https://bugsly.dev) can catch these NestJS errors in real time, giving you stack traces and context to fix issues faster.