Hi there, I have GoDaddy SSL certificate for my own website (https://www.cookieca.com/). The certificate worked fine in all platform, but recently it just doesn't work on iPhone. Here are the details. Note that the certificate is still working on my Mac (Chrome or Safari browser), it is just not working on mobile (iPhone).
The serial number that is associated with the installed certificate appears to be invalid. The most likely cause of this was a certificate re-key.
The re-key process results in a re-issuance of the SSL certificate and once completed requires a subsequent re-install for continued functionality. It is common for some browsers to identify SSL certificates as no longer valid more quickly than others, however, they will all be affected eventually.
To resolve the error, you must download and install the certificate on your server again. Depending on the server platform you are using, you may also be required to create a new CSR and key on the server before proceeding. The information on how to successfully complete the re-key process from start to finish is available here.