Common SSL Certificate Errors

Elisa Keller
Digital Marketing Strategist
February 28, 2024

When you visit a secure website, what underpins that comforting padlock icon is, more often than not, an SSL certificate—a digital passport validating the site's identity. However, there are instances when SSL certificates become the source of elusive errors that compromise the trust and flow of information. In this article, we’re peeling back the layers to unveil the common SSL certificate errors that can disrupt your serenity. From expired certifications to wrong hostnames, self-signed slips to untrusted CAs, and the perplexing incomplete chains, we will succinctly break down each problem.

Introduction to SSL Certificate Errors

Imagine browsing the web and seeing a notice saying your connection is not private; this is often due to an SSL certificate error. SSL certificates are pivotal for website security, serving as digital passports that establish an encrypted connection between a web server and a browser. When these certificates are properly implemented, they ensure that data transmitted is secure and protected from malicious entities that might be eavesdropping.

When issues arise, they manifest as SSL certificate errors, alerting users and potentially halting traffic to your site. The most encountered SSL certificate errors include Certificate Expired, where the SSL certificate has surpassed its validity period; Wrong Hostname, indicated by a mismatch between the certificate's information and your domain; dealing with a Self-signed Certificate, which lacks third-party validation; Untrusted CA, where the issuing certificate authority isn't recognized as reliable; or an Incomplete Chain, which signals missing certificates in the trust hierarchy. Understanding these errors is essential, as they can affect user trust and website credibility.

Certificate Expired

Imagine trying to visit a secure website when suddenly, your browser displays a warning - 'Your connection is not private.' This message indicates that the SSL certificate has expired, a common issue that serves as an expiration timeout for the certificate's validity. SSL certificates are critical for maintaining the integrity and encryption of the websites you visit. Like a driver's license or a passport, these certificates have an expiration date to ensure their credentials are up-to-date and secure.

When a certificate expires, it means that the encryption is no longer reliable and users can no longer trust the connection to the website. This is not just inconvenient - it can also pose a security risk as it leaves the door open for potential attacks or fraudulent activity. Expired certificates significantly undermine the trust that users place on the digital landscape, often resulting in a drop in website traffic and a tarnished reputation for your online presence.

This is where website monitoring tools such as WatchSumo come into play. One key feature of our service is the ability to monitor the expiration dates of your SSL certificates. We provide timely alerts, ensuring you have ample opportunity to renew your certificates ahead of time, so you can take preemptive actions to maintain your site's security.

Wrong Hostname

When you encounter a Wrong Hostname SSL certificate error, it's essentially a mismatch problem. The SSL certificate was issued for a specific domain or set of domains, and these are listed in the certificate's 'Subject' or 'Subject Alternative Name' (SAN) field. If the domain you're trying to access doesn’t match any name in the 'Subject' or 'SAN', you'll be greeted with this error.

This can happen for various reasons, such as if a website has recently changed its domain name but hasn’t yet updated its SSL certificate, or if there's a misconfiguration on the server that serves a certificate meant for another domain. It is crucial that the domain name in the browser matches exactly with one of the names listed in the certificate, including subdomains. If not, your browser will flag the connection as insecure, indicating to you, or your site's visitors, that there could be a potential security risk.

Self-signed Certificate

While attempting to secure your website, you might consider using a self-signed certificate as a quick and cost-free solution. Essentially, self-signed certificates are generated by the server rather than by a trusted certificate authority (CA). At first glance, this might seem like a convenient option, but it comes with significant drawbacks.

Self-signed certificates are inherently less trustworthy since there’s no third-party verification of your website’s identity. When users visit your site, their browsers will often display a security warning, alerting them that the certificate isn't issued by a recognized CA. This can erode trust and result in potential visitors hesitating to proceed to your site, fearing security issues. Additionally, self-signed certificates may not be as rigorous in encryption standards, leaving your site more vulnerable to cyber attacks. For these reasons, they are typically not recommended for public-facing production websites, and you are much better off investing in a certificate from a trusted authority, ensuring the privacy and security everybody expects.

Untrusted CA

When your browser flags an SSL certificate because it's issued by an Untrusted CA (Certificate Authority), you're encountering a rather common but serious SSL error. This happens because your browser maintains a list of trusted CAs, and if an SSL certificate was issued by an authority not on that list, the browser cannot validate the certificate's authenticity. It's akin to getting a passport from a country that's not recognized by the one you're trying to enter – it simply doesn't hold water.

On a deeper level, this also indicates a potential security risk. An untrusted CA might not follow strict guidelines for issuing certificates, increasing the chances of a certificate being issued to a fraudulent website. This is why your browser takes no chances and warns you before proceeding. Addressing this issue typically involves obtaining a new SSL certificate from a reputable, trusted CA to ensure users can access your site without hitting security warnings that could erode trust and harm your site’s credibility.

Incomplete Chain

Encountering an Incomplete Chain error usually means that there is an issue with your SSL certificate chain. Essentially, when your browser tries to verify the legitimacy of a website, it does so by following a 'chain of trust' from the SSL certificate on the server through a series of intermediate certificates up to a root certificate authority (CA). A partial chain exists if your server fails to provide one or more of these intermediate certificates. Consequently, browsers and other clients don't have the complete path needed to establish trust, and a security warning may be displayed.

An Incomplete Chain error is often caused by incorrect server configuration. For instance, when installing your SSL certificate, you might have overlooked an intermediate certificate or installed them in the wrong order. To resolve this issue, ensure that all necessary intermediate certificates are correctly installed on your server in the correct sequence. Fixing this will help clients navigate the chain of trust smoothly, resulting untouched your website's integrity and trustworthiness.


In essence, identifying and resolving SSL certificate errors is of paramount importance for ensuring your website’s credibility and security. From the troubling 'Certificate Expired' message to the dire warning of a 'Wrong Hostname', each variant of SSL error presents a unique challenge to your website’s integrity. The shadow of 'Self-signed Certificates' and the potential pitfalls of an 'Untrusted CA' stand as testament to the importance of robust security measures. Moreover, the intricacies of an 'Incomplete Chain' error underscore the necessity for meticulous management of certificate infrastructure.

Fortunately, with WatchSumo's vigilant monitoring, you can be proactively informed of impending SSL certificate expirations and mishaps. WatchSumo can monitor all these SSL certificate errors and more, keeping your website fortified against intrusive eyes and preserving user trust.