HTTP 500 Internal Server Error

What 500 means

Common causes

• An unhandled exception: TypeError: Cannot read properties of undefined, a null from the database, an unexpected third-party response shape.
• A missing or wrong environment variable in production (DATABASE_URL, API keys) that was set locally.
• Database problems: exhausted connection pool, a migration that hasn't run, a query referencing a column that doesn't exist yet.
• Express 4 doesn't catch errors from async handlers. Without next(err) the rejection is unhandled and the request hangs or the process crashes. Express 5 forwards rejected promises to the error handler.
• Next.js: an error during server rendering or in a Route Handler. In production the browser only sees a generic message with a digest you can search for in the server logs.
• PHP fatal errors with display_errors off, or an invalid directive in Apache's .htaccess.
• Serverless: the function crashed or ran out of memory. Vercel reports 500: FUNCTION_INVOCATION_FAILED.

How to find and fix a 500

# nginx in front of your app
sudo tail -f /var/log/nginx/error.log

# App running under systemd
journalctl -u myapp -f

# Docker
docker logs -f --tail 200 myapp

# Vercel
vercel logs https://my-app.vercel.app

// Express 4: forward async errors (Express 5 does this for you)
const asyncHandler = (fn) => (req, res, next) =>
  Promise.resolve(fn(req, res, next)).catch(next);

app.get('/api/report', asyncHandler(async (req, res) => {
  res.json(await buildReport(req.query));
}));

// Last middleware
app.use((err, req, res, next) => {
  const id = crypto.randomUUID();
  console.error(id, err);
  res.status(500).json({ error: 'internal_error', id });
});

// app/dashboard/error.tsx
'use client';

export default function Error({
  error,
  reset,
}: {
  error: Error & { digest?: string };
  reset: () => void;
}) {
  return (
    <div>
      <p>Something went wrong. Reference: {error.digest}</p>
      <button onClick={() => reset()}>Try again</button>
    </div>
  );
}

Headers that matter with 500

Cache-Control: no-store

Stops a CDN from caching a transient error page.

X-Request-Id

Not standardised, but a request ID in the response makes it easy to find the matching log line.

500 vs similar status codes

• 502 Bad Gateway: A proxy couldn't get a valid response from the app at all. With 500, the app itself responded with the error.
• 503 Service Unavailable: A known, temporary condition (maintenance, overload). Tells clients that retrying later is expected to work.
• 504 Gateway Timeout: A proxy gave up waiting for the app.

SEO impact of 500

When Googlebot sees many 5xx responses it slows its crawling. A short outage is fine, but URLs that keep returning 500 are eventually dropped from the index. Watch your 5xx rate and the server errors in Search Console's Crawl Stats report.

Related status codes

Looking for another code? Search the full HTTP status codes list, or read which code your API should return in the REST API status codes guide.

Learn more

Browse all developer guides →

Frequently Asked Questions