'Website Redirects with .htaccess 403 Forbidden

we got website which has very long domain name longUrlweb.com and we got shortUrl.com which redirects to longUrlweb.com however shortUrl.com stopped redirecting and gives now "403 Forbidden You don't have permission to access / on this server. " error message, if I add www to url www.shortUrl.com it works fine and redirects to longUrlweb.com as it should.

Here is what I got in shortUrlweb htaccess file:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^shortUrl.com$ [OR]
RewriteCond %{HTTP_HOST} ^www.shortUrl.com$
RewriteRule ^ http://longUrlweb.com [R=301,L]

any suggestions please



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