Arabic Characters in URL returns 404 Error

I had same issue as you. I was trying to access the following URL, which results in a 404 error:

The requested URL `/abb/public/main/category/كمال` was not found on this server.

http://localhost/abb/public/main/category/كمال
or
http://localhost/abb/public/main/category/%D9%83%D9%85%D8%A7%D9%84

while accessing
http://localhost/abb/public/main/category/فتنس
http://localhost/abb/public/main/category/%D9%81%D8%AA%D9%86%D8%B3
or
http://localhost/abb/public/main/category/ABCDEF
works fine.

I found the cause of issue in .htaccess file. It was:

RewriteRule ^(.)$ abb/index.php?/$1 [L]

and I changed it to:

RewriteRule ^(.)$ abb/index.php?/$1 [NC,L]

and then it worked.