Drush 8.0.3 is unable to update D7 modules I have Drush installed via Homebrew on my Mac. I am currently unable to execute "drush up" in a Drupal web site. When I attempt, I get the error:

Destination directory [...] already exists.

Is this normal? Do I need to use a different version? Do I need to stop using Homebrew?
You could be hitting this issue - there is a bug if you have a version control system such as SVN installed.

If it is this bug, the error should go away if you pass --version-control=backup.  Of course you will then lose some integration with your version control system.