Mozilla removed support for the non-standard (keygen) HTML element and HTMLKeygenElement DOM interface in Firefox 69. This aligns with the trend following other leading browsers:
This change does not affect active code signing certificates. They can be used until they expire.
When you generate the CSR for a code signing certificate, use Microsoft Internet Explorer or Apple Safari.
If your customer's or your environment only permits usage of Firefox, consider using Firefox ESR or a portable copy of Firefox.
For more information, see our knowledge base article.
If you have questions or concerns, please contact Partner Support at sslpartnersupport@digicert.com.