I am trying to install a feature on an existing site with that already has some of the same field names (field_image for example), and I get the following error:
FieldException: Cannot change an existing field's type. in field_update_field() (line 230 of /var/aegir/platforms/dcpl-drupal7/modules/field/field.crud.inc).
This is related to #1058902: Error when enabling Debut Article, where they recommended:
This bug can be fixed following an approach used in media_gallery.install, which detects existing fields and throws a hook_requirements() error if there's an existing field with the same name but a different type. Arguably this should go in features, but a workaround in debut_article and other debut features meanwhile is important.