apache - RewriteRule Error: Bad flag delimiters

Question

Using this RewriteRule in my .htaccess file I'm getting RewriteRule: Bad flag delimiters which is returning a 500 error in the browser. Can anyone point me in the right direction please. Thanks.

RewriteEngine On

RewriteCond %{HTTP_HOST} ^example.com [NC]

RewriteRule ^dev/(.*)$ http://dev.example.com/$1 [L,R=301, NC]

This is on Ubuntu on a Digital Ocean Droplet.

Answer 1

Turns out it was because of the space before N in the flag declaration [L,R=301, NC]. I changed it to [L,R=301,NC] and now it works a treat.