I have just tried to update drupal 8 beta2 to drupal 8 beta 3

I have received this error. Any sugestion?

Thank you. Regards.

drush pm-update projects drupal-8.0.0-beta3 Update information last refreshed: Wed, 11/12/2014 - 17:30 Name Installed Version Proposed version Message Drupal 8.0.0-dev 8.0.0-dev Specified version available projects Unknown Unknown Specified project not found

Code updates will be made to drupal core. WARNING: Updating core will discard any modifications made to Drupal core files, most noteworthy among these are .htaccess and robots.txt. If you have made any modifications to these files, please back them up before updating so that you can re-create your modifications in the updated version of the file. Note: Updating core can potentially break your site. It is NOT recommended to update production sites without prior testing.

Do you really want to continue? (y/n): y copy(): Filename cannot be empty drush.inc:736 [warning] Unable to download to /home/anubis/public_html from [error] Updating project drupal failed. Attempting to roll back to previously installed version. [error] Backups were restored successfully.