Since you mentioned redirecting 80->443 I'm guessing the issue is/was with HTTP vs HTTPS and one of them was generating links that the other wouldn't serve.
ProxyRequests Off # reverse proxy to serverA/siteA 022718 <Location "/siteA"> ProxyPass http://serverA/siteA ProxyPassReverse http://serverA/siteA Order allow,deny Allow from all Authtype Basic Authname "Restricted Access" AuthUserFile /etc/apache2/.htpasswd Require user ****** </Location> # reverse proxy to serverB/siteB 051418 <Location "/siteB"> ProxyPass http://serverB/siteB ProxyPassReverse http://serverB/siteB Order allow,deny Allow from all Authtype Basic Authname "Restricted Access" AuthUserFile /etc/apache2/.htpasswd Require user ******* </Location>