HTTP to HTTPS redirect exposes subdirectory instead of redirecting to subdomain - apache

Question

After several hours of research, I give up!
When I type this: https://scan.example.com (note HTTPS) it works fine.
But when I type this in browser: http://scan.example.com
it goes to: https://example.com/scan (it puts the subdomain at the end)
How do I prevent this and make sure it goes to https://scan.example.com?
Here is my current .htaccess (Which works perfectly for me for everything else besides the issue above):
Options -MultiViews
RewriteEngine On
# HTTP to HTTPS canonical redirect
RewriteCond %{HTTP_HOST} example\.com [NC]
RewriteCond %{SERVER_PORT} 80
RewriteRule (.*) https://example.com/$1 [R=301,L]
# Abort early if the request already maps to (or looks like) a file or directory
RewriteCond %{REQUEST_URI} \.\w{2,4}$ [OR]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
# 3. Extensionless URLs for other requests
RewriteCond %{DOCUMENT_ROOT}/$1.php -f
RewriteRule (.*) $1.php [L]
*PS: The reason I have example.com/$1 is because I want to be able to access for example account.php in root like this:
https://example.com/account.

Answer 1

I assume your .htaccess file is located in the root directory of the example.com host, in which /scan is a subdirectory (that the subdomain presumably points to)? And this .htaccess file should apply to both the domain apex and the subdomain?
In which case you'll need to use the REQUEST_URI server variable instead of the $1 backreference in the substitution string. Since the $1 backreference will contain the /scan subdirectory when you request the subdomain.
Try the following instead:
# HTTP to HTTPS canonical redirect
RewriteCond %{HTTP_HOST} example\.com [NC]
RewriteCond %{SERVER_PORT} 80
RewriteCond %{HTTP_HOST} ^(?:www\.)?(.+?)\.?$ [NC]
RewriteRule ^ https://%1%{REQUEST_URI} [R=301,L]
Note sure why you have the first condition, unless you are hosting multiple domains?
The above will remove the www subdomain, but will preserve any other subdomain, including scan. However, this does not specifically canonicalize www to non-www, since it only redirects HTTP.