Directing Non-Slash URL to Slash - apache

Question

When I enter the website.com/seo link, I want to make a 301 redirect to the website.com/seo/ link. However, I don't want it to be broken in the codes I wrote in the current htaccess.
my htacces codes:
RewriteEngine On
RewriteBase /
RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s([^.]+)\.php [NC]
RewriteRule ^ %1/ [R=301,L]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.*?)/?$ $1.php [NC,L]

Answer 1

Based on your shown samples, could you please try following. Please clear browser cache before testing your URLs
RewriteEngine ON
RewriteBase /
RewriteCond %{REQUEST_URI} !/$
RewriteRule ^ http://%{HTTP_HOST}%{REQUEST_URI}/ [R=301,L,NE]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s([^.]+)\.php [NC]
RewriteRule ^ %1/ [R=301,L]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.*?)/?$ $1.php [NC,L]

Answer 2

Use only one of these, do not use together!
Try:
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_URI} !^\/(.*?)\/$
RewriteRule ^(.*)$ http://%{HTTP_HOST}%{REQUEST_URI}/ [R=301,L,NE]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s([^.]+)\.php [NC]
RewriteRule ^ %1/ [R=301,L]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.*?)/?$ $1.php [NC,L]
If that doesn't work, use:
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_URI} !^\/(.*?)\/$
RewriteRule ^(.*)$ http://%{HTTP_HOST}%{REQUEST_URI}/ [R=301,L,NE]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.*?)/?$ $1.php [NC,L]
Remove the previous rules, and try once. If it works after removing previous rules, then let me know.