You’ve probably seen those browser warnings: ”Your connection is not private” or ”This site is not secure.” For visitors landing on your website, these messages are instant trust-killers. Most will hit the back button before you even know they were there. The frustrating part? Many of these SSL certificate problems are completely preventable.
I’ve been monitoring SSL certificates for websites across different industries, and I keep seeing the same mistakes pop up again and again. These aren’t just technical nuances that only affect security experts – they’re real issues that can cost you customers, damage your reputation, and even get you flagged by search engines. Let’s walk through the five most common SSL mistakes and, more importantly, how to avoid them.
Letting Your Certificate Expire Without Warning
This is hands down the most common SSL mistake I encounter. Your certificate has an expiration date, typically after one year, and if you don’t renew it in time, your website becomes inaccessible to visitors. Browsers will throw up aggressive warning screens, and many users won’t risk proceeding.
The problem usually isn’t forgetting about renewal entirely – it’s that the renewal happens at the wrong level of your organization or the notification emails go to an old address that nobody checks anymore. I’ve seen businesses lose significant revenue because their certificate expired on a Friday afternoon and nobody noticed until Monday morning.
The solution is straightforward: set up proper monitoring that checks your certificate status daily and alerts you well before expiration. Ideally, you want warnings starting at 30 days out, then again at 14 days, 7 days, and daily in that final week. This gives you multiple chances to handle renewal, even if someone’s on vacation or the first notification gets missed.
Using Self-Signed Certificates on Production Sites
I get it – self-signed certificates are free and easy to generate. They’re perfect for development environments or internal testing. But they have no place on a public-facing production website.
Here’s why this matters: when you use a self-signed certificate, there’s no trusted third party (Certificate Authority) vouching for your website’s identity. Browsers rightfully treat this as suspicious and show warning messages to your visitors. Even if you click through the warnings yourself during testing, your customers won’t. They’ll see ”potential security risk” and assume your site might be compromised or fake.
The good news is that legitimate SSL certificates are now either very affordable or completely free through services like Let’s Encrypt. There’s simply no reason to use self-signed certificates on production websites anymore. If budget is a concern, free options provide the same level of browser trust as paid certificates for standard encryption needs.
Incomplete Certificate Chain Installation
This one’s a bit more technical, but it trips up a lot of website owners. SSL certificates work on a chain of trust – your certificate needs to link back to a trusted root certificate through intermediate certificates. If you only install your primary certificate without the intermediate certificates, some browsers and devices won’t be able to verify the trust chain.
The symptoms of this problem are sneaky. Your website might work fine in Chrome on your desktop but fail on older smartphones or certain browsers. You might not even notice the issue because it works for you, but a portion of your audience is getting security warnings.
About a year ago, I worked with an e-commerce site that was mysteriously losing mobile customers during checkout. Turned out their intermediate certificate wasn’t properly installed, and mobile browsers were showing security errors that desktop browsers somehow handled gracefully. They were losing sales and had no idea why.
When you install an SSL certificate, always verify that you’ve included the full certificate chain. Most Certificate Authorities provide a ”bundle” or ”chain” file that includes everything you need. Use online SSL checker tools to verify your installation shows the complete chain.
Ignoring Mixed Content Warnings
You’ve installed your SSL certificate, and your website loads with that reassuring padlock icon in the browser. Perfect, right? Not necessarily. If your HTTPS pages are loading images, scripts, or other resources over HTTP (non-secure connections), you’ve got mixed content issues.
Modern browsers handle mixed content in different ways. Some will block insecure resources entirely, breaking your website’s functionality or design. Others will show a ”not secure” warning even though you technically have a valid SSL certificate. Either way, you’re undermining the security you paid for.
This commonly happens after migrating from HTTP to HTTPS. Your pages are now secure, but somewhere in your code or database, there are still old HTTP links to images, CSS files, JavaScript libraries, or embedded content. Each of these creates a potential security hole and definitely creates a trust problem with browsers.
The fix requires hunting down and updating all these references to use HTTPS instead. Check your templates, your database content, and any third-party scripts you’re loading. Browser developer tools can help identify mixed content warnings. Once you’ve cleaned everything up, consider implementing Content Security Policy headers to prevent mixed content from sneaking back in.
Using Certificates on the Wrong Domain or Subdomain
SSL certificates are issued for specific domain names. If you have a certificate for ”www.example.com” but someone visits ”example.com” (without the www), they might get a security warning. Or if your certificate covers your main domain but not your subdomains like ”shop.example.com” or ”blog.example.com”, you’ve got problems.
This mistake often happens when businesses expand their web presence without updating their SSL strategy. You start with a simple website, add a blog on a subdomain, then an online shop on another subdomain, and suddenly you’re juggling multiple certificates or leaving some properties unprotected.
The solution depends on your setup. For most businesses, a wildcard certificate that covers your domain and all its subdomains makes sense. If you have multiple distinct domains, you might need either separate certificates for each or a multi-domain certificate that covers all of them. The key is planning your SSL coverage to match your actual domain structure.
Staying Protected: A Continuous Process
SSL certificate management isn’t a one-time setup task. It requires ongoing attention to expiration dates, proper configuration, and adapting to new security standards. The good news is that once you have proper monitoring in place, most of these issues become easy to catch before they affect your visitors.
Whether you manage SSL certificates yourself or rely on hosting providers, the important thing is having systems that actively watch for problems. Automated monitoring catches expiring certificates, configuration issues, and other SSL problems before they impact your business. It’s about moving from reactive firefighting to proactive prevention.
Your SSL certificate is a fundamental part of your website’s trustworthiness. Taking the time to avoid these common mistakes means your visitors can focus on what you’re offering instead of worrying whether your site is safe.