How to Fix DatabaseError in NestJS When Deploying

Running into a DatabaseError in NestJS? This guide walks you through the root cause and a practical fix.

Why This Happens

A DatabaseError when deploying 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.

How to Fix It

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

One pitfall to avoid: applying a quick workaround that disables the underlying safety check. This masks the real problem and will come back to haunt you when deploying. Consider adding a health check endpoint or startup validation that catches this misconfiguration before it reaches users.

Testing Your Changes

Run your test suite to make sure the fix doesn't introduce regressions. If you don't have tests covering this area, now is a good time to add a simple integration test. A quick manual smoke test across different browsers or environments can also catch edge cases your tests might miss.

Monitoring

Want to catch errors like this before they reach production? [Bugsly](https://bugsly.dev) provides real-time error tracking for NestJS applications.