Underscores in apache virtual host names

I have always used dashes in my vhost names.

I only use underscores in filenames.

This is just a dev machine. For Community Auth I had been using localhost.community_auth_ci_3. I've been using underscores for years, and then all the sudden they're not allowed. The worst part was that Apache's error message was vague, and I initially thought I had a typo in the vhost file.

Expert Website Development - Temecula, CA
Community Auth For CodeIgniter 3