Right way to update a drupal distribution? I have a site which is a Commerce Kickstart distribution.

My distribution version is 7.x-2.0-rc1 and now the 7.x-2.0-rc2 version is available.

How do I update a distribution? I tried these method (both failed...)

1) I follow the update standar process using the drupal ui. I get this error message:

&gt;     Notice: Undefined index: version_major in update_calculate_project_update_status() (line 595 of
&gt; /Applications/MAMP/htdocs/mySite.com/modules/update/update.compare.inc).
&gt;     Downloading updates failed:
&gt;     
&gt;     commerce_kickstart-7.x-2.0-rc2-core.tar.gz does not contain any .info files.
&gt;     Notice: Undefined index: version_major in update_calculate_project_update_status() (line 595 of
&gt; /Applications/MAMP/htdocs/mySite.com/modules/update/update.compare.inc).


2) I downloaded the distribution and replace the folder mysite.com/profiles/commerce_kickstart
This didn't work neither.

¿Which is the right way to to do this?
You should try it with drush. 

drush dl commerce_kickstart
drush updatedb -y


(I have not tried it for commerce kickstart; I just got the answer on drupal.org.)