media_gallery_file already exists and is not of type file. Installation cannot continue.

After upgrading to 2.x-dev, and running update.php, I get these notices/errors:

media_gallery_file already exists and is not of type file. Installation cannot continue. Please remove this field or change its type.

Notice: Undefined index: title in theme_status_report() (line 2577 of C:\Users\Amy\Dropbox\htdocs\com\samesunvt\drupal\modules\system\system.admin.inc).
Notice: Undefined index: value in theme_status_report() (line 2577 of C:\Users\Amy\Dropbox\htdocs\com\samesunvt\drupal\modules\system\system.admin.inc).