removed .html extensions with htaccess now index.html give 403 error - .htaccess

Question

After entering the code below, my home page gives a 403 error. The rest of the site works perfectly. All instances of .html were removed.
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^\.]+)$ $1.html [NC,L]
Any advice?
Thank you!

Answer 1

example.com leads ti the 403 error. If I write example.com/index it works fine.
Something else must have changed for this to result in a 403 error. The code you posted won't actually do anything when you request example.com/ - the same as if that code didn't exist at all. (UPDATE: However, this assumes your .htaccess file is located in the document - it appears this is not the case - see below.)
However, what will trigger a 403 in such cases is when "formatted directory listings" are disabled and the directory index document cannot be found (or has been disabled).
So, try setting the appropriate directory index at the top of your .htaccess file:
DirectoryIndex index.html
It is the DirectoryIndex that serves the appropriate file when requesting your "home page", not your directives in .htaccess.
UPDATE:
It [.htaccess] is located in my root directory. Would it be better to put it in the public_html folder?
Yes, the code you posted should go in the /public_html directory (ie. your document root). If these directives are in a .htaccess file above the document root then the RewriteRule pattern will match the URL-path public_html/ and rewrite the URL to public_html/.html which is possibly where your 403 error is coming from ("dot" files are usually hidden/protected OS files and you may also have a directive in your server config blocking access. However, this behaviour may also be dependent on other factors in the server config/OS). However, with that code in the document root then a request for example.com/ (your home page) won't be processed by these directives (which is good) - mod_dir should then serve the index.html file in this instance.
However, you don't want to process "directories" anyway (public_html is obviously a "directory", not a file). Which is what's happening above. eg. .html shouldn't be appended to public_html/ to begin with (or example.com/path/to/directory/ or any other directory). This can be avoided by adding an additional condition to your rule block to avoid directories (as well as files). For example:
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^.]+)$ $1.html [L]
Simply adding that additional RewriteCond directive might be enough and still allow you to keep your .htaccess file above the document root. (However, you may still need to move the .htaccess file as well, as described above.)
Also, the NC flag is not required here and literal dots don't need to be escaped when used inside a character class.
You could also extend this code to first check the existence of the file (with a .html extension) before rewriting, although this may be unnecessary in your case. For example:
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.html -f
RewriteRule ^([^.]+)$ $1.html [L]
This requires an additional "file check" which may be an unnecessary overhead.