How to Fix DatabaseError in Express

Dealing with a DatabaseError in your Express project? You're in the right place. Let's solve this step by step.

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 configure pg Pool with proper timeouts and add a health check endpoint:

const { Pool } = require("pg");

const pool = new Pool({
  connectionString: process.env.DATABASE_URL,
  max: 20,
  idleTimeoutMillis: 30000,
  connectionTimeoutMillis: 2000,
});

pool.on("error", (err) => {
  console.error("Unexpected pool error:", err);
});

// Health check endpoint
app.get("/health", async (req, res) => {
  try {
    await pool.query("SELECT 1");
    res.json({ db: "connected" });
  } catch (err) {
    res.status(500).json({ db: "disconnected", error: err.message });
  }
});

Common Pitfall

If this error appears intermittently, it likely points to a race condition or resource exhaustion issue rather than a simple misconfiguration. Check your connection pool settings and timeouts. Adding a comment in your configuration explaining why this setting exists will save your future self — and teammates — hours of confusion.

Verify the Fix

After applying the fix, restart your Express 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

To prevent this from recurring unnoticed, set up [Bugsly](https://bugsly.dev) for your Express project — it monitors errors and gives you actionable alerts.