CI 框架访问 http://[::1]/yourproject/

Chances are you have left the base url blank
/*
|--------------------------------------------------------------------------
| Base Site URL
|--------------------------------------------------------------------------
|
| URL to your CodeIgniter root. Typically this will be your base URL,
| WITH a trailing slash:
|
|   http://example.com/
|
| WARNING: You MUST set this value!
|
| If it is not set, then CodeIgniter will try guess the protocol and path
| your installation, but due to security concerns the hostname will be set
| to $_SERVER['SERVER_ADDR'] if available, or localhost otherwise.
| The auto-detection mechanism exists only for convenience during
| development and MUST NOT be used in production!
|
| If you need to allow multiple domains, remember that this file is still
| a PHP script and you can easily do that on your own.
|
*/

$config['base_url'] = '';

Go to application/config/config.php set base_url

$config['base_url'] = 'http://localhost/example/';

Then ::1 error should be gone.

Now days in latest versions of codeIgniter it is not recommend that you leave your base_url blank.

• $config['base_url'] = 'http://localhost/yourproject/';
• $config['base_url'] = 'http://www.example.com/';

And is always good to end url with /

二：此原因及升级版本后，CodeIgniter-3.0.6\system\core\Config.php 构造函数体内  $_SERVER['SERVER_ADDR']  造成，改成 $_SERVER['HTTP_HOST']，做相应调整亦可。