How to Fix “Subdomains Don’t Support Secure Encryption Algorithms”

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If Semrush flags “Subdomains don’t support secure encryption algorithms” during an audit, it means the security (encryption) on parts of your website, like blogs or shops, isn’t strong enough.

How to fix "Subdomains don’t support secure encryption algorithms"

Does it affect the ranking? Solving this problem helps to increase the ranking of your website in search engines. Google and other search engines prefer secure sites and rank them higher. In addition, if you don’t fix it, your site and its visitors can become vulnerable to hackers, and you definitely want to avoid this.

In this post, we’ll show you how to fix it, ensuring every visitor can use your site securely.

How to fix the “Subdomains do not support secure encryption algorithms” error

Fixing the “Subdomains do not support secure encryption algorithms” error involves a few steps, focused on updating and configuring your website’s SSL/TLS certificates. SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are the protocols that provide the encryption for your website.

Follow these simple steps:

1) Identify the Affected Subdomains

How many Subdomains don’t support secure encryption algorithms"

The SEMrush audit report should list which subdomains have this issue. Take note of them. These are the parts of your website you’ll be focusing on.

2) Check Your SSL/TLS Certificate

The most common fix involves checking your SSL/TLS certificate, which is responsible for encrypting data on your site. You’ll want to make sure that:

  • Your certificate is up to date and hasn’t expired.
  • Your certificate covers all the subdomains listed in the error. Sometimes, a certificate might cover your main domain but not its subdomains.

3) Update your certificate

If your certificate is all good but you’re still seeing the error, it might be time to upgrade your encryption algorithm. This usually means reaching out to your hosting provider or whoever manages your website’s security and asking them to use a more modern encryption method. Most reputable providers will handle this for you, often at no extra cost.

4) Redirect to HTTPS

4. Redirect to HTTPS.

Make sure that all your subdomains are automatically redirected from HTTP to HTTPS. This ensures that every visitor uses a secure connection. You can do this by adding a few lines to your .htaccess file if you’re using Apache, or by adjusting your web server configuration if you’re using something else.

5) Test again

After making these changes, use the SSL test again to make sure everything is set up correctly. You should see that your subdomains support secure encryption algorithms.


The “Subdomains don’t support secure encryption algorithms” error might seem daunting at first, but with a little patience and the right approach, you can fix it and make your site safer for everyone who visits. Remember, the goal here is to ensure that your website is a secure place for your visitors. Reach out to a professional if you need more help.

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