id summary reporter owner description type status priority milestone component version severity resolution keywords cc focuses 30459 is_child_theme() cannot be used during plugin activation as is cais "I was developing a plugin that was based on a specific theme (or any child-theme of the theme) and tried to use `is_child_theme()` as part of the activation/compatibility tests. It appears `is_child_theme()` is trying to use undefined constants at this point, this being the case the easiest solution I am seeing is to use the constant definitions in `is_child_theme()` versus using the constants themselves. With the constants an error is thrown when the plugin is activated, with the function calls no errors are thrown. See simple patch to change `is_child_theme()` from using constants to using the actual function calls." defect (bug) new normal Themes 3.0 normal has-patch bulk-reopened