Message: Configured database connection is persistent. Aborting

I had the same issue, and found that it was just a matter of changing a setting:

Modify your database.php config file and turn 'pconnect' to false. As part of the CI 3 Framework, it would be part of this array:

$db['default'] = array(    'pconnect' => FALSE // This value);

Or if your config file looks more like the CI 2 version:

$db['default']['pconnect'] = FALSE;

A bit of searching seems to suggest that the database doesn't like a persistent connection, possible because of security reasons.

Disable caching in database.php file, define caching folder in database.php by

'cachedir' => APPPATH.'cache/db/',

setting and only use

$this->db->cache_on(); 

command where you want your database query being cached.

Don't forget to use

$this->db->cache_off();

after select queries for unwanted cached results.

It seems like codeigniter 3.0 doesn't support sessions using database, when persistent is enabled.form: http://www.codeigniter.com/user_guide/libraries/sessions.html?highlight=session#session-preferences

However, there are some conditions that must be met:

Only your default database connection (or the one that you access as $this->db from your controllers) can be used. You must have the Query Builder enabled. You can NOT use a persistent connection. You can NOT use a connection with the cache_on setting enabled.