Troubleshooting 'Failed Websocket': How to Fix Closed Connection Before Establishment Issues

Websockets provide a powerful way to enable real-time, bidirectional communication between a client and a server. However, sometimes the websocket connection can fail, resulting in a closed connection before the establishment. In this guide, we'll walk you through the steps to troubleshoot and fix 'failed websocket' issues.

Table of Contents

  1. Identify the Issue
  2. Check Your Server Configuration
  3. Inspect Client-Side Issues
  4. Inspect Network Issues
  5. FAQs

Identify the Issue

Before diving into the troubleshooting process, it's important to identify the issue causing the failed websocket. This can be done by examining the error message or logs related to the issue.

Some common error messages related to websocket failures include:

  • "WebSocket connection to 'ws://' failed: Error during WebSocket handshake: Unexpected response code: 400"
  • "WebSocket is already in CLOSING or CLOSED state."
  • "WebSocket connection failed: WebSocket opening handshake was canceled."

These error messages can help you pinpoint the problem and apply the appropriate solution.

Check Your Server Configuration

A common cause of failed websocket connections is misconfiguration on the server-side. To fix this, follow these steps:

Step 1: Verify Websocket Support

Ensure that your server supports websockets and has the necessary modules or extensions installed. For example, for an Apache server, you may need to enable the proxy_wstunnel module:

sudo a2enmod proxy_wstunnel
sudo systemctl restart apache2

For an Nginx server, ensure that the ngx_http_websocket_module is included in your configuration.

Step 2: Examine Server Logs

Check your server logs for any error messages or warnings related to websockets. This can help you identify the root cause of the problem.

Step 3: Adjust Configuration Settings

Make sure your server configuration supports websocket connections. For example, in an Nginx configuration, you may need to add a location block to handle websocket connections:

location /websocket {
    proxy_pass http://websocket_backend;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";

Inspect Client-Side Issues

Sometimes, the issue may lie on the client-side. To troubleshoot this, follow these steps:

Step 1: Check Browser Support

Ensure that the browser being used supports websockets. You can use a website like Can I use to check browser compatibility.

Step 2: Examine Browser Console

Open the browser console and check for any error messages or warnings related to websockets. This can help you identify the issue and apply the appropriate fix.

Step 3: Verify WebSocket URL

Ensure that the websocket URL being used on the client-side is correct and follows the proper format, e.g., ws://

Inspect Network Issues

Network issues can also cause websocket connections to fail. Follow these steps to troubleshoot network-related problems:

Step 1: Check Firewall Settings

Ensure that your firewall and security settings allow websocket connections. You may need to add a rule to allow connections on the port used by your websocket server.

Step 2: Test Network Connection

Test the network connection between the client and server using tools like ping or traceroute. This can help you identify any connectivity issues that may be causing the websocket failure.

Step 3: Monitor Network Traffic

Use network monitoring tools like Wireshark to inspect the network traffic between the client and server. This can help you identify any issues related to packet loss, latency, or other network problems.


1. What is a websocket?

A websocket is a communication protocol that enables two-way communication between a client and a server over a single, long-lived connection. This allows for real-time updates and reduces the latency associated with traditional HTTP requests.

2. Why am I getting a 'failed websocket' error?

A 'failed websocket' error can be caused by a variety of issues, such as server misconfiguration, client-side problems, or network issues. You'll need to troubleshoot the problem to identify the root cause and apply the appropriate fix.

3. How can I test my websocket connection?

You can use online tools like Echo Test or browser developer tools to test your websocket connection and identify any issues.

4. Can I use websockets with a load balancer?

Yes, you can use websockets with a load balancer. However, you'll need to ensure that your load balancer supports websocket connections and is properly configured to handle them.

5. Are there any alternatives to websockets for real-time communication?

Yes, there are several alternatives to websockets for real-time communication, such as Server-Sent Events (SSE), long polling, and WebRTC. Each of these technologies has its own advantages and disadvantages, depending on your specific use case.

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