An SSL certificate error can mean two very different things depending on who you are. If you’re browsing a website and it suddenly refuses to load, that’s one problem. If it’s your own business website throwing the error at customers, that’s a different problem entirely, and usually a more urgent one.
We’ll go through both, starting with the quicker one.
If you’re just trying to visit a website
Before assuming anything is broken on a large scale, try these in order. Most of the time one of the first three sorts it out.
Check the date and time on your device. This sounds too simple to matter, but a clock that’s out of sync can make a perfectly valid certificate look expired to your device, and it’s a more common cause than people expect.
Clear your browser’s cache and cookies, then reload the page. Browsers sometimes hold onto an old, expired version of a certificate rather than checking for the current one.
Try opening the site in an incognito or private window. If it loads fine there, something in your regular browser, usually an old cached certificate or an extension, is the actual cause.
Turn off any VPN or antivirus software that scans secure connections, then try again. Some antivirus tools intercept HTTPS traffic to scan it, and occasionally that process itself is what triggers the error.
Try a different browser or device on the same network. If the site loads properly somewhere else, the problem is local to your original browser, not the website.
If none of that works and the error still shows up everywhere you try, the certificate issue is likely genuine and sitting on the website’s end, not yours. At that point, the safest move is simply not entering any personal or payment details until it’s fixed.
What the common browser messages actually mean
Chrome, Firefox, Safari and Edge all phrase this differently, but they’re usually pointing at one of a few issues.
A message about the certificate being expired means exactly that, the certificate’s validity period has run out and needs renewing.
A message about the certificate authority not being trusted usually means the certificate was self signed, or issued by an authority the browser doesn’t recognise.
A name mismatch message means the certificate was issued for a different domain than the one you’re actually visiting, which often happens after a site changes domains or adds a new subdomain without updating the certificate to match.
If it’s your own website
This is where it stops being an inconvenience and starts being a business problem, because every visitor hitting that warning is a visitor who’s about to leave.
Check the expiry date first. It’s the single most common cause, and it’s almost always avoidable. Certificates typically run for around a year and need renewing before they lapse, not after.
Check the certificate chain. A valid certificate can still trigger errors if the intermediate certificates linking it back to a trusted authority weren’t installed correctly. This is a common one because it’s invisible from your own browser if your device has already cached the missing piece, so it can sit broken for weeks before someone actually reports it.
Check that the certificate matches every domain you’re serving. If your site loads under both the www and non www version, or across multiple subdomains, the certificate needs to cover all of them, otherwise visitors on the version it doesn’t cover will see an error while everyone else is fine.
Check for mixed content. If your page loads over HTTPS but pulls in an image, script or font over plain HTTP, some browsers will flag the whole page as insecure even though the certificate itself is fine.
A real example of how this quietly costs a business money
We picked up a client a while back whose website had been showing an intermittent certificate warning for almost two weeks before anyone noticed. Nobody internally had seen it because the office computers already had the certificate cached from before it broke. Customers landing on the site for the first time were getting a full browser warning and, understandably, most of them were leaving rather than clicking through it. The cause turned out to be a missing intermediate certificate after a server migration, not the actual certificate itself. It took under an hour to fix once we found it, but it had likely been quietly turning away new visitors the entire time it went unnoticed.
That’s the pattern worth remembering. SSL errors rarely announce themselves loudly to the people who can actually fix them. They show up to new visitors first, and the business is often the last to know.
How to stop this happening again
The simplest fix is not having to remember it manually. Most certificate problems come down to renewal dates slipping past unnoticed, so setting up monitoring that alerts you before a certificate is due to expire removes the guesswork entirely. If you want a plain explanation of how SSL certificates and DNS work together in the first place, our guide on DNS and SSL explained covers the basics without the jargon.
For a deeper technical read on what causes certificate errors and browser handling, Google’s own support page on connection privacy errors is a solid reference if you want to go further than we’ve covered here.
If you’d rather not deal with this yourself
Certificate renewals and DNS configuration are easy to get wrong once, and the cost of getting them wrong is usually lost customers rather than a technical inconvenience. We manage DNS and SSL for businesses across Sydney so renewals happen automatically and nobody finds out about a problem from a customer complaint. If your certificate has thrown an error recently, or you’d simply rather stop thinking about it, get in touch with our team and we’ll sort it properly.
FAQs
Why am I seeing an SSL certificate error on a website I’ve visited before without issue? It’s often a timing issue on your own device, such as an incorrect clock or a cached version of an old certificate. Clearing your cache or trying an incognito window usually confirms whether the problem is on your end or the website’s.
Is it safe to continue to a website showing an SSL certificate error? It’s best to avoid entering any personal details or payment information until the error is resolved. Occasionally it’s a harmless technical mix up, but there’s no way to tell that from the warning alone, so treating it cautiously is the safer default.
How do I fix an SSL certificate error on my own website? Start by checking whether the certificate has expired, then confirm the intermediate certificate chain is installed correctly and that the certificate covers every domain and subdomain your site actually serves.
What causes an SSL certificate to suddenly stop working after a server migration? Usually a missing intermediate certificate. The main certificate can still be valid, but without the correct chain linking it back to a trusted authority, browsers will flag it as untrusted even though nothing looks wrong at first glance.
How often do SSL certificates need to be renewed? Most certificates run for around one year, though some shorter lived certificates renew more frequently. Setting up an expiry alert well in advance is the easiest way to avoid it lapsing unnoticed.
Can an SSL certificate error affect my website’s search rankings? Indirectly, yes. Search engines favour secure sites, and a certificate error will also drive visitors away before they engage with your content, both of which can affect how a site performs over time.
