Troubleshooting guide

When deploying an application, you might see HTTP errors like 403, 404, 502, 503, or 504. These typically mean the app is up but not behaving as expected. Here's what each error means and how to fix it.

403 – Forbidden

The application is running, but the server is refusing access to the requested resource.
This usually points to permission issues—either on the application side or server config.

How to fix it

Check if the path requires authentication or restricted roles.
Review access rules in your app or framework.
Make sure static files or endpoints are exposed correctly.

404 – Not Found

The application couldn’t find the requested path or file.
This often means a route is missing, or the app isn’t serving static content as expected.

How to fix it

Verify that the route or file exists.
If using a frontend framework (e.g., React, Vue), make sure client-side routing is handled correctly.
Check your build output and redeploy if needed.

502 – Bad Gateway

The deployment succeeded, but Dash couldn’t connect to your application.
Your app might have crashed, or it isn't listening on the expected port.

How to fix it

Check logs to look for crashes or port binding issues.
Ensure your application starts without errors and listens on the correct port.
Check your Dockerfile or start command if using a custom container.

503 – Service Unavailable

Dash couldn't serve your application—typically due to a temporary issue.
The application might still be starting up, restarting, or failing health checks.

How to fix it

Wait a few seconds and try again.
Use logs to see if the application is in a crash loop.
Check memory usage or deployment status in the Dash UI.

504 – Gateway Timeout

Dash couldn’t get a response from your application in time.
Your application took too long to start up or respond to the request.

How to fix it

Optimize slow startup or request handling.
Break long-running processes into background tasks if possible.
Use logs to identify bottlenecks or timeouts.

Need more help?

Reach out on Discord — the team and community are happy to help.