Getting No route matches "index.html.var" errors

Hello,
My Ruby app has been running for the last two months on Hostgator with no issues. I have not changed one line of code.

All of a sudden, on March 9th, trying to access my website using the base URL ( not the actual domain, but I'll use it for this post http://www.example.com) is throwing the following errors (from /log/production.log)

[4;36;1mSQL (0.5ms)[0m   [0;1mSET SQL_AUTO_IS_NULL=0[0m
Processing ApplicationController#index (for 174.114.60.37 at 2019-03-16 08:10:22) [GET]
ActionController::RoutingError (No route matches "/index.html.var" with {:method=>:get}):

My routes.db file is shown below:

ActionController::Routing::Routes.draw do |map|
map.root :controller => "mylittleapp"
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format' end

My htaccess file is shown below

RewriteEngine on
RewriteCond %{HTTP_HOST} ^example\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.example\.com$
RewriteCond %{REQUEST_URI} !^/\.well-known/acme-challenge/[0-9a-zA-Z_-]+$
RewriteCond %{REQUEST_URI} !^/\.well-known/cpanel-dcv/[0-9a-zA-Z_-]+$
RewriteCond %{REQUEST_URI} !^/\.well-known/pki-validation/[A-F0-9]{32}\.txt(?:\ Comodo\ DCV)?$
RewriteRule ^(.*)$ "http\:\/\/127\.0\.0\.1\:12006\/$1" [P,L]

HOWEVER, if I try to access the Ruby app using http://www.example.com/mylittleapp, then the app is accessible and everything works fine.
Key points:

1. The website has been working fine for two months and is accessible from the base URL, so I know that Rails was routing it to the correct ActionController.
2. I have not made any code changes to the site
3. Something mysteriously changed and now "index.html.var" is being passed in and the Rail Router cannot find a route, so it throws an error and calls 404.html
4. The actual Ruby app is operational, but just not accessible from its base URL. My suspicion is that Hostgator changed either a .httpd config flag or modified my .htaccess file. Any suggestions on how to resolve this? Thanks