Yes, I apologize for not making that very clear.   I was speaking of Apache modules, which are loaded with the LoadModule directive in httpd.conf.   For some reason, Apache no longer thinks that it’s supposed to be loading this module, or it’s no longer successfully doing so.

AFAIK, Apache’s architecture is to first load the various modules, effectively as extensions to its core, then to present each incoming configuration directive to each one of them.   If Apache “suddenly doesn’t know what you’re talking about,” it’s because a module, not the core, is what knew about it all along.