8.79% of HTTPS sites have certificate problems that trigger a browser warning. When a visitor sees "Your Connection Is Not Private" or "Not Secure", most leave immediately, without reading further.
What certificate errors mean
Your TLS certificate is issued by a trusted certificate authority and tied to your domain name. It tells browsers: this site is who it claims to be. Certificate errors happen when that proof breaks down. The certificate has expired, it was issued for a different domain, the issuing authority isn't trusted, or the chain of trust is incomplete.
Each browser (Chrome, Firefox, Safari) blocks access by default when it detects a certificate error. Users see a full-page warning before they can reach your site.
The business cost
- Visitors bounce immediately; there is no softer outcome than a full-page "not private" warning
- Contact forms, quote requests, and purchases on HTTPS pages with certificate errors are abandoned
- Search engines detect certificate problems and may demote or stop indexing affected pages
- Enterprise due diligence checks flag certificate errors as evidence of poor security management
What causes them and how to fix each
An expired certificate is the most common cause. Let's Encrypt certificates auto-renew every 90 days; configure auto-renewal and this never happens again. Most hosts and CDNs offer this as a one-click setting.
A domain mismatch means your certificate was issued for www.yourdomain.com but visitors reach yourdomain.com (or vice versa). Reissue the certificate with both covered, or redirect all traffic to the covered form.
An incomplete chain means the certificate itself is valid, but the intermediate certificates connecting it to the root CA aren't installed. Upload the full certificate chain, including the intermediates.
A self-signed certificate is valid for internal tools, never for public websites. Replace with a CA-signed certificate.
What your domain scores right now
Run the free DomainScores check to see your current certificate grade alongside 34 other security checks. Instant, no signup.
Don't want to do this yourself? Domain Fix from €1,197: we fix certificates and every other failing check. Grade B+ guaranteed, or your money back.