How to Fix ERR_SSL_PROTOCOL_ERROR?

Encountering ERR_SSL_PROTOCOL_ERROR is often a deal breaker for website visitors who interpret it as an issue in website security. This is a critical consideration because visitors value security above all else at websites such as eCommerce stores.

Fixing the issue should be the priority of website administrators because of this perception. The issue becomes acute in the case of e-commerce stores and similar websites because of the negative perception that propagates through word-of-mouth and social media.

In this comprehensive guide, we will take a close look at the ERR_SSL_PROTOCOL_ERROR. In addition, we will see why this error happens on a typical website. Finally, we will discuss several strategies to fix the ERR_SSL_PROTOCOL_ERROR issue and remove the error from your website.

What is ERR_SSL_PROTOCOL_ERROR?

Before we go into the details of fixing the ERR_SSL_PROTOCOL_ERROR, we should understand what leads to causing this error on a website.

The Anatomy of The ERR_SSL_PROTOCOL_ERROR

Given the security challenges modern websites face, the end-to-end communication between the server hosting the website and the browser passes through a channel that is encrypted by an SSL/TLS certificate. This secure tunnel is essential for protecting sensitive information such as login credentials and credit card details. The ERR_SSL_PROTOCOL_ERROR indicates that something is wrong with this security component.

When a user enters the URL of a website in their browser, the browser and the server initiate a process that covers several steps before a secure connection is established between the two entities. This process is known as the handshake (or more precisely, the SSL/TLS handshake). An important purpose of this handshake is to validate the identity of the client and the server and ensure that they exchange the keys used for the encryption of data packets moving through the secure tunnel.

The major steps in this process are:

Initialization: The browser initiates the connection by sending a simple Hello message to the server.

Response: The server acknowledges the initial message and sends the identity certificate to the browser. Both parties agree upon a suitable encryption suite/method.

Verification: The browser verifies and authenticates the server’s identity.

Exchange: The server and the browser exchange encryption keys that they will use to encrypt the data in the secure tunnel.

Data Transfer: Both parties do a final check and start exchanging encrypted data.

In case of a disruption in the steps of the handshake, the connection between the server and the client will not happen. This triggers the ERR_SSL_PROTOCOL_ERROR, indicating that one or more of the following has occurred:

• The browser and the server cannot agree on the SSL/TLS certificate versions
• There is a mismatch between the keys required for encrypting the data.
• The handshake process is interrupted before completion

Factors Behind ERR_SSL_PROTOCOL_ERROR

As mentioned earlier, the root cause of the ERR_SSL_PROTOCOL_ERROR is an interruption in the SSL/TLS handshake. Since there are two sides to this handshake process (the server and the client), the process can break down on either side.

Here are some common issues that can happen on the server and the browser side and cause the ERR_SSL_PROTOCOL_ERROR in the visitors’ browser.

On the server side:

• You have a revoked SSL certificate on the server
• The installed SSL/TLS certificate is expired
• The DNS A record is not properly configured
• The server is unable to enforce an HTTPS connection

Alternatively, on the client side:

• The local firewall is blocking the incoming connection
• One or more extensions/plugins in the browser is causing the failure
• The QUIC protocol is breaking the encryption (usually in Chromium-based browsers)
• The system has an incorrect time/date.

Note that one or more of these issues can happen on either side. Similarly, one or more issues can happen on both sides to cause the ERR_SSL_PROTOCOL_ERROR in the visitors’ browsers.

How to Fix the ERR_SSL_PROTOCOL_ERROR?

Now that you know what causes the ERR_SSL_PROTOCOL_ERROR and the underlying factors that contribute to this issue, let’s see how you can fix it.

Since the problems causing the error can lie on the server or the browser’s side (or maybe both), we have decided to present the fixes you can apply on the server and browser separately.

Let’s start with the fixes for servers

Solutions for Website Administrators

In many cases, users will inform you when they face the issue in their browsers. Fortunately, you can apply the following fixes to ensure the visitors do not see the error in their browsers.

Fix #1: Verify TLS Protocol Version(s) in Use

A very common issue that causes the ERR_SSL_PROTOCOL_ERROR is the server running a deprecated version of the TLS certificate. This usually triggers the error because modern browsers reject the handshake because of security concerns. More specifically, you should note that all TLS and SSL versions except TLS 1.2 and TLS 1.3 are deprecated and no longer recommended for active use.

We will demonstrate how you can modify the specific configuration file of an Apache server to ensure it is using TLS versions 1.2 and 1.3.

Open the Apache SSL configuration file in your preferred text editor. We will open it in Nano with this command

# nano /etc/apache2/mods-available/ssl.conf

Locate the SSLCipherSuite parameter in the file to enable secure ciphers:

SSLCipherSuite HIGH:!aNULL

Next, set the value of the Enable SSLHonorCipherOrder parameter to on with this modification:

Enable SSLHonorCipherOrder on

Finally, set the value of the SSLProtocol to ensure that the server uses TLS 1.2 and TLS 1.3:

SSLProtocol all +TLSv1.2 +TLSv1.3

Save the file and exit.

Next, you need to make sure the changes are enforced by restarting the Apache service:

# systemctl restart apache2

Fix #2: Check the Status of the SSL Certificate

An expired, revoked, or improperly installed SSL certificate is frequently responsible for SSL errors. Check the status of your certificate by following the steps below:

You should frequently check the status of the installed SSL/TLS certificate to make sure that the certificate is current and has not been revoked or otherwise expired. Similarly, an improperly configured or installed certificate can also cause an error in the browser.

Checking the status of the server SSL/TLS certificate is simple.

Open the website in a new browser tab and click the padlock or Site Information button in the Address Bar.

You can see that the certificate installed on the RedSwitches website is valid. You can get further information by expanding the certificate information link

Pay special attention to the certificate expiration date and make sure that either you have the certificate on auto-renewal or have a new valid certificate ready to replace the expired one.

Fix #3: DNS Issues

DNS A records contain the IP address of a domain, specifically the IPv4 address. Improperly configured DNS A records can also cause the ERR_SSL_PROTOCOL_ERROR.

A mismatch in the IP addresses can cause the browser to show the ERR_SSL_PROTOCOL_ERROR. For instance, improperly configured DNS A (address) records can have a different IP address of the domain. As such, you should check the publicly visible IPv4 address with this command syntax:

# dig <your domain> +short

If there is a mismatch between the IP address you set for your domain and what you see in the terminal, you should check the DNS A records of your domain and update the record.

Fix #4: Force HTTPS

Almost all SSL certificates force the use of HTTPS. However, there is a slight chance that this happens without the use of SSL encryption on the website. As a result, visitors see the ERR_SSL_PROTOCOL_ERROR in the browser.

We strongly recommend checking the SSL certificate provider and the hosting provider documentation so that you can confirm whether the SSL encryption is available on your website.

Fix #5: Check for Mixed Content Warnings

An overlooked source of the ERR_SSL_PROTOCOL_ERROR is the mixed content issue. Here, most website assets and content load over HTTPS while the rest load over HTTP. This conflict leads to conflicts that culminate in SSL errors at the front end.

The resolution of this issue is simple–you should update all assets and content to load over HTTPS only. This may require some changes in how the code and assets are handled on the server. In addition, you can also opt for WordPress (or other CMS) plugins that force-load everything over HTTPS.

You can also set up 301 redirects on the server for all HTTP content. This requires modifying the .htaccess on an Apache server. For this open the file in your preferred browser and add the following lines:

RewriteEngine On

RewriteCond %{HTTPS} off

RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Similarly, if you are running NGINX on your server, you should add a redirect block in all server blocks:

server {

listen 80;

server_name <your_domain> <www.your_domain.com>;

return 301 https://your_domain.com$request_uri;

}

Remember to clear server cache to make sure all previously cached rules are removed and the new rules are applied.

Fix #6: Update Server Security

SSL certificates and encryption are part of the overall server security operations.

As such, you should focus on improving the security of the server to ensure that all security components and processes are updated. This involves following weekly and monthly server and infrastructure security checklists. Make sure that these lists include checking the status of SSL certificates so that you can identify expiring certificates and replace them before they can compromise security.

Solutions for End Users

If you are browsing a website and see the ERR_SSL_PROTOCOL_ERROR, we recommend going through these steps.

Solution #1: Temporarily Disable Antivirus and Firewall

Sometimes, the ERR_SSL_PROTOCOL_ERROR is triggered because of heightened system security. In particular, the system firewall can prevent some websites from functioning properly in your browser. In addition, on Windows machines, the on-system antivirus program can also contribute to the issue.

When you see the ERR_SSL_PROTOCOL_ERROR, a quick fix is to temporarily disable the firewall (and antivirus) and revisit the website in a new browser tab. Remember to re-enable the firewall and antivirus to ensure continued security.

Solution #2: Disable Browser Extensions

Browser extensions enhance the core browser capabilities by adding new functionalities. Under the hood, these extensions tap into the core browser codebase to provide the required features.

A side effect of using browser extensions is unexpected behavior and errors, including the ERR_SSL_PROTOCOL_ERROR.

If you suspect this to be the case, the simple fix is to disable all browser extensions.

For this, visit the dedicated extension management page of your browser. For instance, in Google Chrome, this page is available at this address:

chrome://extensions

Now toggle the installed extensions off to disable them.

Now, reload the website in a new tab to confirm that the issue is resolved.

Remember to toggle the extensions on to continue enjoying the functionalities of the extensions.

Solution #3: Disable the QUIC Protocol

QUIC is an experimental UDP-based protocol developed to improve the performance of Google web apps. Deactivating it in Chrome forces the browser to use HTTP instead of HTTPS, which can help you access the website.

Google developed the QUIC protocol to enhance the capabilities of their web applications. It is a UDP protocol that significantly improves the performance of applications that use the traditional TCP protocol. The protocol forces the use of HTTPS and thus can cause issues in how the browser renders a website.

You can disable the protocol to see if it is causing the ERR_SSL_PROTOCOL_ERROR.

Go to this address in a new Chrome tab:

chrome://flags

In the search box at the top, search for QUIC. Next, choose DISABLE from the drop-down to disable the use of the protocol.

Solution #4: Check System Clock

Do you know that the TLS handshake process uses the values of your system clock (time and date) as part of the validation process? As such, you should make sure that the system clock is set to the proper time and date. Similarly, you should also make sure that your system clock is set to use the appropriate timezone.

If you are using a Linux distribution on your system, the simplest way of ensuring that your system has the right time is to set the right timezone in the Date and Time application.

Similarly, on Windows systems, go to Settings and then Time & Language > Date & Time Settings to set the correct system time.

Solution #5: Clear Cookies and Browser cache

In some cases, a corrupted browser cache can cause a mismatch between the local and remote values of variables related to TLS handshake and SSL certificates.

Similarly, SSL encryption also encrypts cookies as the data is exchanged between the server and the browser.

We recommend following your browser’s documentation to clear the cache and stored cookies. You can also selectively delete cookies and cache data for the website where you encountered the error.

Here is how this option looks like in Google Chrome

Conclusion

The ERR_SSL_PROTOCOL_ERROR can disrupt secure connections, but identifying whether it’s a server or client-side issue is key to resolving it.

By following targeted solutions for both website administrators and end-users, you can address this error efficiently. Maintaining updated SSL/TLS protocols and security settings ensures a smoother, safer browsing experience for all users.

FAQs

Q. What is ERR_SSL_PROTOCOL_ERROR, and why does it occur?

ERR_SSL_PROTOCOL_ERROR is a security error that indicates a problem with establishing a secure connection. It can be caused by issues with SSL/TLS protocols, server configurations, or client settings.

Q. How can an outdated browser cause ERR_SSL_PROTOCOL_ERROR?

An outdated browser may not support the latest SSL/TLS protocols, causing compatibility issues. Updating to the latest version can resolve the error by ensuring compatibility with current security standards.

Q. What role does the certificate authority (CA) play in SSL errors?

A certificate authority verifies the authenticity of SSL certificates. If a website’s certificate is issued by an untrusted or invalid CA, browsers may block access and display the ERR_SSL_PROTOCOL_ERROR.

Q. How does clearing the SSL state fix this error?

Clearing the SSL state in your browser or operating system removes old certificates and session data, helping resolve SSL handshake issues that may trigger the error.

Q. Can antivirus software cause ERR_SSL_PROTOCOL_ERROR?

Yes, antivirus software can interfere with SSL connections by performing HTTPS scanning. Temporarily disabling this feature can help determine if it’s causing the error.

Q. What does the authentication process have to do with this error?

During the SSL/TLS authentication process, the client and server exchange certificates. If this process fails due to certificate mismatches or trust issues, it may result in ERR_SSL_PROTOCOL_ERROR.

Q. Why is the ERR_SSL_PROTOCOL_ERROR common on public Wi-Fi networks?

Public Wi-Fi networks often have insecure configurations or may use captive portals that interfere with SSL connections, resulting in SSL protocol errors.

Q. How do I know if the problem is with my device or the website?

Check if the error occurs on multiple devices or networks. If it does, the issue likely lies with the website’s server settings or SSL certificate.

Q. How does clearing the browser cache help fix ERR_SSL_PROTOCOL_ERROR?

Outdated cache files may conflict with SSL validation, leading to errors. Clearing the cache can help by forcing the browser to fetch updated data from the server.

Q. What steps should website administrators take to fix ERR_SSL_PROTOCOL_ERROR?

Administrators should verify their SSL certificates, ensure they’re from a trusted CA, update TLS protocols, and resolve any DNS or server configuration issues.

Q. Can an expired SSL certificate trigger this error?

Yes, an expired SSL certificate fails the authentication process, which can result in ERR_SSL_PROTOCOL_ERROR. Administrators should renew certificates before they expire to avoid this issue.

Q. How can I disable the QUIC protocol to fix this error in Google Chrome?

In Chrome, type chrome://flags in the address bar, search for QUIC Protocol, and disable it. This can help resolve SSL errors associated with experimental QUIC protocol conflicts.