A clear path forward
My app shows "Application failed to respond"—what does that mean?
“Application failed to respond” means your app is not listening on the port Replit expects.
Your app needs to use the PORT environment variable, the port setting Replit passes to it. Use that setting in your app's server setup instead of a fixed port number.
These examples read the setting and use 3000 if it is not set:
JavaScript
const PORT = process.env.PORT || 3000;
Python
import os
port = int(os.environ.get("PORT", 3000))
These lines only read the port number. Your app's server still needs to listen on that port.
Your app may also have stopped before it could listen for requests. Check your deployment logs for startup errors.
With Autoscale deployments, the first request after a quiet period can take a few seconds. This startup delay is called a cold start.
Did this get you unstuck?
Still stuck?
See what to include and open a support ticket.
Still stuck?
See what to include and open a support ticket.If this page did not solve it, contact Support and describe what you were trying to do and what happened, in your own words. You do not need to gather anything in advance.
Include in your ticket, if you know it
- What you were trying to do
- What happened, in your own words
- What you have already tried, if anything
Copying is optional. No ticket is submitted and no files are attached automatically; send your request in the support form.
Do not include passwords, API keys, or payment-card details.