Between Jan 10th 11:21 CST and Jan 23rd 14:03 CST, submitting a CSR during the DigiCert SSL certificate configuration process may result in an error on some systems that run WHMCS 8.2 and earlier:

Invalid CSR Provided

An unknown error occurred

An issue within the WHMCS Marketplace caused this error on WHMCS 8.2 and earlier. 

This issue did not affect WHMCS 8.3 and later.

We have resolved the issue by applying a fix directly to the WHMCS Marketplace. You will not need to perform any additional actions.

Any orders that encountered the error can resubmit the certificate configuration, which will now be successful. For more information, see How To Manually Configure an SSL Certificate.