How to Fix Proxy Error Could Not Proxy Request (Step by Step)

Seeing the dreaded “Proxy error: Could not proxy request” can be confusing, especially if you’re not sure whether it’s a coding problem or a network one.

This error usually means that a proxy server (like the one in React, Vite, or a corporate network) tried to forward your request to another server but failed. The good news? You can fix it by following a structured troubleshooting process.

Why Does “Could Not Proxy Request” Appear?

When you set up a proxy, it acts as a middleman: your client sends a request to the proxy, which then forwards it to the backend server. If the proxy cannot reach the target, it throws this error. The most common reasons include:

• The backend server is not running or listening on the expected port.
• The proxy configuration points to the wrong host or URL.
• HTTP and HTTPS protocols are mismatched.
• CORS rules or SSL certificates block the request.
• Network or firewall restrictions interfere with the proxy.

In some cases, misrouting leads to similar failures, such as when a proxy server cannot establish connection with target, which looks almost identical from the user’s perspective.

Step-by-Step Fixes for Proxy Error Could Not Proxy Request

Before jumping into complex solutions, start with the basics. Each step below helps isolate where the problem lies.

1. Check if the Backend Server Is Running

Your proxy will not work if the target server is down. Open a browser or use curl/Postman to test the backend directly:

curl https://localhost:5000/api/ping

If it does not respond, start or debug your backend first. A non-responsive server often triggers cases like proxy error no response from bot pgshag2, where requests never reach their destination.

2. Verify Ports and Host Binding

Make sure your backend listens on the right port and accepts connections.

• On Windows: netstat -ano | findstr :5000
• On macOS/Linux: lsof -i :5000

If another process is blocking the port, kill it and restart the server. Port conflicts may also cause related IP proxy error issues when the system misroutes requests.

3. Confirm Your Proxy Configuration

Double-check that your proxy points to the correct target.

app.use('/api', createProxyMiddleware({
target: 'https://localhost:5000',
changeOrigin: true,
secure: false
}));


Misconfigured paths can produce different failures, from a proxy error 500 (internal error at the proxy) to a proxy error 2606, which is often tied to unreachable addresses.

4. Match Protocols (HTTP vs HTTPS)

If your backend runs with HTTPS, your proxy must use https://. Mixing protocols will trigger errors. For local dev with self-signed certificates, set secure: false. Wrong protocol handling can sometimes bubble up as proxy error 503, signaling that the service is temporarily unavailable.

5. Rule Out CORS Problems

During development, always call your backend through the proxy (e.g., /api/users). Avoid direct cross-origin calls. If unavoidable, configure backend headers like:

Access-Control-Allow-Origin: https://localhost:3000

When servers throttle repeated cross-origin calls, you may even hit limits similar to a proxy error 429, which means too many requests.

6. Handle Timeouts and Large Payloads

If requests are heavy, increase timeouts in the proxy:

proxyTimeout: 120000,
timeout: 120000


Timeouts may also surface as strange variations such as repairing IP address proxy error, where unstable connectivity creates broken routing.

7. Fix WebSocket Support

If your app uses subscriptions or HMR, set ws: true in your proxy configuration. Ensure both proxy and backend allow WebSocket upgrades. Some image-heavy workflows may instead show a proxy not working for this image warning if media requests fail at the proxy layer.

8. Troubleshoot Docker or WSL2 Networking

When working in containers:

• Use https://host.docker.internal:5000 to connect host and container.
• Map ports explicitly in Docker compose.
• For service-to-service traffic, use the service name (e.g., https://backend:5000).

9. Reverse Proxy Checks (Nginx/Apache)

If you’re using a production reverse proxy:

location /api/ {
  proxy_pass https://localhost:5000/;
  proxy_http_version 1.1;
  proxy_set_header Connection "";
}

Reload the config after changes.

10. Watch for Firewall, VPN, or Corporate Proxy Issues

If everything works locally but not in a company environment, your IT firewall may block certain ports. Whitelist localhost or disable the VPN temporarily to test.

Developer vs End-User Proxy Errors

Context	Typical Error	Who Fixes It
Developer	Could not proxy request, ECONNREFUSED, ETIMEDOUT	Developer checks backend, config, or ports
End-User	502 Bad Gateway, 504 Timeout, Proxy Auth Required	IT team, website operator, or user fixes settings

Tips to Avoid Proxy Errors

• Always align frontend proxy routes with backend API paths.
• Use relative URLs (/api/...) in development, not absolute ones.
• Enable detailed logs (logLevel: 'debug') for clearer error tracking.
• Restart both frontend and backend when in doubt.

Smart Way to Fix Proxy Error Could Not Proxy Request

By systematically checking backend availability, proxy rules, and network conditions, you can quickly isolate and resolve the issue. Whether you’re a developer running React locally or an end-user behind a corporate proxy, these steps cover the most common fixes.

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