When using PATH_INFO , the urls of codeignitor apps or your custom MVC looks like this
index.php/controlller/method/param1/param2 or /controlller/method/param1/param2
Now if the parameters contain a forward slash then you would urlencode it as :
But opening that kind of URL would give an error : Page Not Found
This happens if AllowEncodedSlashes directive of Apache is not turned on. More Here. This directive should be turned on to allow those sort of Urls. And for codeignitor $config['permitted_uri_chars'] should also be checked to allow forward slash in uri characters.
1. Apache Documentation