Sometimes, codeigniter does not support session on server but everything fine on localhost using wampserver or Xamp or etc.
So you cannot login on server, because most of login techniques uses session on PHP.
Here let’s solve the issue:
You may use use codeigniter older version, so you need to upgrade without losing your programs codes.
So just download new codeigniter file and replace ‘system‘ folder on your project and upload again to server.
You don’t need to specify ‘base_url’ on your project configuration.
Your .htaccess file may be like this:
RewriteCond $1 !^(index.php|assets|images|css|js|icon|uploads|build|robots.txt)
RewriteRule ^(.*)$ /index.php/$1 [L]
No need to specify project name on server.