Error: Class 'Drupal' not found in bootstrap.inc Please tell me what I'm doing wrong. I'm unable to run drush, see error below:

[~/public_html/d8]# drush -d status
Bootstrap to phase 0. [0.01 sec, 1.86 MB]                            [bootstrap]
Drush bootstrap phase : _drush_bootstrap_drush() [0.01 sec, 1.98 MB] [bootstrap]
Cache HIT cid:                                                       [debug]
6.0-rc4-commandfiles-0-6046c80192c5b97fbcd88f24c7e529ed [0.02 sec, 1.99 MB]
Bootstrap to phase 0. [0.09 sec, 5.27 MB]                            [bootstrap]
Drush bootstrap phase : _drush_bootstrap_drupal_root() [0.14 sec, 5.28 MB] [bootstrap]
Initialized Drupal  root directory at /home3/public_html/d8    [notice] [0.15 sec, 5.39 MB]
Drush command terminated abnormally due to an unrecoverable error.   [error]
Error: Class 'Drupal' not found in /home3/public_html/d8/core/includes/bootstrap.inc, line 164  [0.15 sec, 5.4 MB]


I'm using:


Drush Version   :  6.0-rc4 
drupal 8.0.0-beta7  
PHP 5.4.38    
MySQL 5.5.42-37.1
Drush 6.x only works with Drupal 6 or 7, upgrade to Drush 7.x.

Source