Installed the html viewer 1.2 template and my sites are now broken

Hello all,

Maybe someone here can help with this. I installed the html5 1.2 viewer template on GE 3.8 following the instructions provided using the post installer. After I was finished my existing silverlight sites(which have been running fine for months) are broken. When they are accessed the critical error "Cannot open configuration file" is thrown.

When I go into the Rest manager and click on the REST API Sites Directory URL a page comes up saying "Service Unavailable".  The Geocortext Agent service is running. I can open the sites for editing, but when I click on viewer for a site and then the edit button for the viewer I get a message saying;

Sorry, an error occurred while processing your request.

Unable to load viewer configuration. The file 'http://[local server name]/Geocortex/Essentials/Instance/REST/sites/MapViewer/Viewers/Mapviewer/VirtualDirectory/Config/Viewer.xml' or one of the referenced external configurations could not be read or has errors. See log file for more details.

I've tryed a few of the tips in some related threads like editing the manager web.config and changing the EssentialsUrl to the external url, but that didn't help.

Any help would be appreciated. Thanks.