CodeIgniter by default won’t allow you to use query strings in the URL.
This is how you enable query string in url in codeigniter.
1. Set $config[‘uri_protocol’] = “PATH_INFO” in config.php
2. Set $config[‘enable_query_strings’] = TRUE in config.php
3. Make you sure you have QSA in your .htaccess. For example,
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond $1 !^(index\.php|images|includes)
RewriteRule ^(.*)$ /index.php/$1 [L,QSA]
Note: If you make these changes, the pagination module is affected. So, if you had implemented any pagination before changing these settings, you might want to check them again.