iPhone SSL issues: what happened and how to fix it

If you received an SSL warning on your iPhone after we updated the certificates on our shared servers, you are not alone. The certificates installed on the shared servers expired and were replaced with new ones. Most devices picked up the change without any issues, but iPhones running older versions of iOS sometimes hold on to cached certificate data, which causes the warning to appear even though the new certificate is valid.

The fix does not require any changes to your hosting account. It is a device-side cache issue, and clearing it takes a couple of minutes.

Why iPhones show this warning after a certificate renewal

When your browser or device connects to a site over HTTPS, it checks the SSL certificate (a file that proves the site’s identity and encrypts the connection) against a list of trusted authorities. iOS caches some of this information locally to speed up future connections. When a certificate is renewed, the cached data can conflict with the new certificate, triggering a warning that looks more alarming than it is.

This is a known behaviour on iOS, particularly on devices that have not been restarted recently or that are running an older version of Safari’s certificate store.

How to clear the certificate cache on iPhone

The steps below clear Safari’s cached website data, which removes the outdated certificate information stored on your device.

Open the Settings app on your iPhone.
Scroll down and tap Safari.
Tap Clear History and Website Data.
Confirm by tapping Clear History and Data in the prompt that appears.
Restart Safari and revisit the site.

If the warning persists after clearing Safari’s data, restart your iPhone entirely. A full restart forces iOS to re-fetch certificate information from scratch rather than relying on anything stored in memory.

Tip: If you use a third-party browser such as Chrome or Firefox on iOS, clear the cache within that app separately. Each browser maintains its own certificate cache.

Checking that the new certificate is valid

Once you have cleared the cache, you can confirm the certificate is working correctly by tapping the padlock icon in Safari’s address bar. This shows the certificate details, including the issuer and expiry date. A valid certificate will show a green padlock with no warnings attached.

If you are still seeing a warning after clearing the cache and restarting, the issue may be something other than cached data. Check that your iPhone’s date and time are set to update automatically, as an incorrect system clock can cause certificate validation to fail regardless of whether the certificate itself is valid.

The certificate renewal on our shared servers is complete, and all sites hosted with us are covered. If you have questions about SSL certificates for your site, our team can help. You are also welcome to get in touch if the warning continues after following the steps above.