Thanks ah72 for your solution. It helped me but there is a little risk with this code.
For example, if you try to go to a page like 'es/modules/directory/subdirectory.html' and you are using spanish language (Joomfish code: es) you will obtain a request like this : 'modul/directory/subdirectory.html' which is wrong.
I changed the following code :
if ( strstr( $request, $my_jfish_prefix."/" ) ) {
$request = str_replace( $my_jfish_prefix."/", null, $request );
break;
}
with this code:
if (substr($request, 0, strlen($my_jfish_prefix) ) == $my_jfish_prefix) {
$request = preg_replace('/^' . $my_jfish_prefix . '\//', '', $request);
break;
}
In this case, it replaces "es/" only if $request begins with "es/".
Please note that this solution works only if the plugin "System - Jfrouter" is configured to work with SEF Prefix.