Strange behaviour of a website after enabling Apache Module


one of the websites i am dealing with on the server needs the headersmodule to work.

What i did:

Enable headers module in Webmin’s Apache config window.

Apply changes

then i added this directive to the virtual servers conf file:

Header add Access-Control-Allow-Origin “*”

Restarted Apache.

Another Website was missing content, menu and various modules.

I commented out that directive in the first virtual servers conf file; disabled the headers module again, restarted Apache, but the error stayed.

So i checked all my log files, just to find … nothing …

Last option i had: Restoring the backup from tonite. So the website is up and running again, but i am wondering, what happened, and what i would have to do in order to have this module running and use it one specific website, where i need it without affecting others, which should not be affected.

Any insight is truly appreciated.

Thanks and best