https://eurossl.eu/2025/12/30/sectigo-legacy-chain-reissuance-ending-december-2025/
Sectigo Notice: Legacy Chain Re-Issuance Will End After December 31, 2025 - euroSSL
Dec 30, 2025 - Sectigo will end support for re-issuing SSL/TLS certificates using legacy trust chains after December 31, 2025. Learn how this affects Microsoft server...