WordPress at a glance
action is not described

pre-upload-ui action-hook . WP 2.6.0

Fires just before the legacy (pre-3.5.0) upload interface is loaded.

Usage

add_action( 'pre-upload-ui', 'action_function_name_8127' );
function action_function_name_8127(){
	// action...
}

Changelog

Since 2.6.0 Introduced.

Where the hook is called

media_upload_form()
pre-upload-ui
wp_print_media_templates()
pre-upload-ui
wp-admin/includes/media.php 1991
do_action( 'pre-upload-ui' );
wp-includes/media-template.php 248
do_action( 'pre-upload-ui' );

Where the hook is used (in WP core)

Usage not found!