How to fix ERR_QUIC_PROTOCOL_ERROR Chrome Error

Despite being a widely-used web browser, Google Chrome is still prone to errors that can hinder your site’s accessibility. One of them is ERR_QUIC_PROTOCOL_ERROR. Unlike most HTTP status code error messages, it occurs when the browser is unable to reach the web server using the QUIC protocol.

Such an error makes your site inaccessible, resulting in a bad reputation and traffic loss.

With this in mind, we will explain the possible causes of the ERR_QUIC_PROTOCOL_ERROR code and three effective methods to troubleshoot it.

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Error code	ERR_QUIC_PROTOCOL_ERROR
Error type	Browser protocol error
Error causes	QUIC protocol Incompatible third-party extensions Incorrect proxy configuration Poor internet connection Compromised SSL certificate

What Causes ERR_QUIC_PROTOCOL_ERROR

When trying to access a web page on Google Chrome, you might encounter ERR_QUIC_PROTOCOL_ERROR, causing the “This site can’t be reached” error message. The message indicates that your site may be temporarily down or moved permanently to a new web address.

Enabled QUIC Protocol in Google Chrome

Google Chrome supports various protocols, including Quick UDP Internet Connections (QUIC). It’s an experimental transport protocol that was designed to optimize web application delivery by reducing web latency.

As it is built on top of the User Datagram Protocol (UDP) instead of Transport Layer Security (TCP), it offers greater security protection and a faster browsing experience. This makes it ideal for gaming and streaming applications, where reliability and low latency are critical.

While QUIC can provide significant performance benefits, the protocol is not as popular as HTTP or HTTPS. As a result, the browser might refuse to load web pages due to compatibility issues.

Chrome Browser Extensions

Essentially, a browser extension is a third-party software that can modify and improve the functionality of web browsers. While most extensions are beneficial, installing incompatible extensions may also trigger the error.

Proxy Settings Issues in Windows

Another possible cause of the ERR_QUIC_PROTOCOL error is an issue with your proxy configuration. When using a proxy server, the web server will exclusively handle all the website requests. Thus, if the proxy server fails to forward the request properly, it may trigger the error.

3 Ways to Fix ERR_QUIC_PROTOCOL_ERROR

Before getting into the troubleshooting methods, we recommend trying some quick fixes first. Here are some solutions to consider when encountering ERR_QUIC_PROTOCOL_ERROR:

• Reload the page with other browsers. Use Google Chrome alternatives such as Firefox, Edge, or Safari to reload the page that shows ERR_QUIC_PROTOCOL_ERROR. If the error message still appears, check whether the website is down or if there’s an issue with your internet connection.
• Clear browser cache. Removing temporary files like expired cookies and cache helps prevent security and connectivity problems.
• Enable the UDP Port 443 at the firewall. As QUIC runs on top of the UDP, you’ll need to verify that the HTTPS port 443 is enabled both on your web server and firewall. This will allow QUIC-enabled browsers and servers to communicate with each other without being blocked by the firewall.
• Check whether your site is using HTTP/3. Since HTTP/3 is required for the QUIC to work, it’s worth checking if your site supports it. Use online tools like HTTP/3 Check to test your site’s QUIC version and HTTP/3 service.

If none of them work, proceed with the following methods:

1. Disable the QUIC Protocol in Chrome

By default, Google Chrome uses QUIC as its primary transport protocol for securing connections between your computer and Google’s servers. 

Since the protocol itself is often the main cause of the error, disabling it might fix the problem. To do so, follow the steps below:

1. Open Chrome and enter chrome://flags into the address bar.

2. Search for the QUIC to access the Experimental QUIC protocol flag.

3. From the drop-down menu, switch from Default to Disabled.

4. Restart Chrome for the changes to take effect.

2. Disable Chrome Extensions

Outdated or poorly-coded extensions can slow down your site and cause connection issues, including the ERR_QUIC_PROTOCOL_ERROR message.

To find out if an extension is causing the problem, open your Chrome extension page to disable it. Here are the steps to do so:

1. Open a new tab on Google Chrome browser and click the three dots icon in the top-right corner.

2. Select More tools → Extensions.

3. To disable extensions, simply click the toggle button next to all of them.

Another way to access the extension page is by typing in a chrome://extensions/ in the URL bar. After disabling all the unwanted extensions, try to restart Chrome to see if the changes take effect. 

3. Check Proxy Settings in Windows

Using a proxy server enables you to improve security and privacy by hiding a user’s IP address from malicious websites. Even so, the incorrect proxy configuration may trigger your browser to return an ERR_QUIC_PROTOCOL_ERROR message.

Thus, if you’re using a proxy, make sure its settings are correct. 

Here’s how to check proxy settings in Windows:

1. Click on Start and use the search bar to locate Control Panel.
2. Navigate to Network and Internet and select Internet Options.

3. The Internet Properties pop-up will appear. Open the Connections tab, and click on the LAN settings button.

4. Uncheck the Use a proxy server for your LAN box and enter the desired settings in the Address and Port fields.

5. Once done, click the OK button to save your settings.

Conclusion

ERR_QUIC_PROTOCOL_ERROR occurs when the Google Chrome browser has trouble connecting to a website via Quick UDP Internet Connections (QUIC). There are multiple reasons behind it, such as problems with the protocol itself, extension issues, or incorrect VPN and proxy server settings.

Luckily, there are a few easy fixes available. Let’s recap three effective methods to fix ERR_QUIC_PROTOCOL_ERROR:

1. Disable experimental QUIC protocol. Quickly resolve the issue by turning off Chrome’s QUIC protocol feature.
2. Check Google Chrome extensions. Try disabling outdated or problematic extensions from the Extensions page.
3. Configure proxy settings. Ensure your operating system’s proxy settings are configured correctly.

In case the error still persists, and it happens on your own website, consider asking your web hosting provider for further assistance.