Index: src/wp-admin/custom-header.php
===================================================================
--- src/wp-admin/custom-header.php	(revision 31408)
+++ src/wp-admin/custom-header.php	(working copy)
@@ -681,8 +681,12 @@
 	 */
 	public function step_2() {
 		check_admin_referer('custom-header-upload', '_wpnonce-custom-header-upload');
-		if ( ! current_theme_supports( 'custom-header', 'uploads' ) )
-			wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+		if ( ! current_theme_supports( 'custom-header', 'uploads' ) ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+				'<p>' . __( 'The current theme does not support uploading a custom header image.' ) . '</p>',
+				403 );
+		}
 
 		if ( empty( $_POST ) && isset( $_GET['file'] ) ) {
 			$attachment_id = absint( $_GET['file'] );
@@ -832,11 +836,19 @@
 	public function step_3() {
 		check_admin_referer( 'custom-header-crop-image' );
 
-		if ( ! current_theme_supports( 'custom-header', 'uploads' ) )
-			wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+		if ( ! current_theme_supports( 'custom-header', 'uploads' ) ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+				'<p>' . __( 'The current theme does not support uploading a custom header image.' ) . '</p>',
+				403 );
+		}
 
-		if ( ! empty( $_POST['skip-cropping'] ) && ! ( current_theme_supports( 'custom-header', 'flex-height' ) || current_theme_supports( 'custom-header', 'flex-width' ) ) )
-			wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+		if ( ! empty( $_POST['skip-cropping'] ) && ! ( current_theme_supports( 'custom-header', 'flex-height' ) || current_theme_supports( 'custom-header', 'flex-width' ) ) ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+				'<p>' . __( 'The current theme does not support a flexible sized header image.' ) . '</p>',
+				403 );
+		}
 
 		if ( $_POST['oitar'] > 1 ) {
 			$_POST['x1'] = $_POST['x1'] * $_POST['oitar'];
Index: src/wp-admin/customize.php
===================================================================
--- src/wp-admin/customize.php	(revision 31408)
+++ src/wp-admin/customize.php	(working copy)
@@ -13,7 +13,10 @@
 require_once( dirname( __FILE__ ) . '/admin.php' );
 
 if ( ! current_user_can( 'customize' ) ) {
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to customize the site&apos;s appearance.' ) . '</p>',
+		403 );
 }
 
 wp_reset_vars( array( 'url', 'return' ) );
Index: src/wp-admin/edit-comments.php
===================================================================
--- src/wp-admin/edit-comments.php	(revision 31408)
+++ src/wp-admin/edit-comments.php	(working copy)
@@ -8,8 +8,12 @@
 
 /** WordPress Administration Bootstrap */
 require_once( dirname( __FILE__ ) . '/admin.php' );
-if ( !current_user_can('edit_posts') )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( !current_user_can('edit_posts') ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to edit posts.' ) . '</p>',
+		403 );
+}
 
 $wp_list_table = _get_list_table('WP_Comments_List_Table');
 $pagenum = $wp_list_table->get_pagenum();
Index: src/wp-admin/edit-tags.php
===================================================================
--- src/wp-admin/edit-tags.php	(revision 31408)
+++ src/wp-admin/edit-tags.php	(working copy)
@@ -17,9 +17,14 @@
 if ( ! $tax )
 	wp_die( __( 'Invalid taxonomy' ) );
 
-if ( ! current_user_can( $tax->cap->manage_terms ) )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( ! current_user_can( $tax->cap->manage_terms ) ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to manage these items.' ) . '</p>',
+		403 );
+}
 
+
 // $post_type is set when the WP_Terms_List_Table instance is created
 global $post_type;
 
@@ -49,8 +54,12 @@
 
 	check_admin_referer( 'add-tag', '_wpnonce_add-tag' );
 
-	if ( !current_user_can( $tax->cap->edit_terms ) )
-		wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	if ( ! current_user_can( $tax->cap->edit_terms ) ) {
+		wp_die(
+			'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+			'<p>' . __( 'You are not allowed to edit create this item.' ) . '</p>',
+			403 );
+	}
 
 	$ret = wp_insert_term( $_POST['tag-name'], $taxonomy, $_POST );
 	$location = 'edit-tags.php?taxonomy=' . $taxonomy;
@@ -85,8 +94,12 @@
 	$tag_ID = (int) $_REQUEST['tag_ID'];
 	check_admin_referer( 'delete-tag_' . $tag_ID );
 
-	if ( !current_user_can( $tax->cap->delete_terms ) )
-		wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	if ( !current_user_can( $tax->cap->delete_terms ) ) {
+		wp_die(
+			'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+			'<p>' . __( 'You are not allowed to delete this item.' ) . '</p>',
+			403 );
+	}
 
 	wp_delete_term( $tag_ID, $taxonomy );
 
@@ -97,8 +110,12 @@
 case 'bulk-delete':
 	check_admin_referer( 'bulk-tags' );
 
-	if ( !current_user_can( $tax->cap->delete_terms ) )
-		wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	if ( !current_user_can( $tax->cap->delete_terms ) ) {
+		wp_die(
+			'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+			'<p>' . __( 'You are not allowed to delete these items.' ) . '</p>',
+			403 );
+	}
 
 	$tags = (array) $_REQUEST['delete_tags'];
 	foreach ( $tags as $tag_ID ) {
@@ -135,8 +152,12 @@
 	$tag_ID = (int) $_POST['tag_ID'];
 	check_admin_referer( 'update-tag_' . $tag_ID );
 
-	if ( !current_user_can( $tax->cap->edit_terms ) )
-		wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	if ( !current_user_can( $tax->cap->edit_terms ) ) {
+		wp_die(
+			'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+			'<p>' . __( 'You are not allowed to edit this item.' ) . '</p>',
+			403 );
+	}
 
 	$tag = get_term( $tag_ID, $taxonomy );
 	if ( ! $tag )
@@ -248,8 +269,12 @@
 
 require_once( ABSPATH . 'wp-admin/admin-header.php' );
 
-if ( !current_user_can($tax->cap->edit_terms) )
-	wp_die( __('You are not allowed to edit this item.') );
+if ( !current_user_can($tax->cap->edit_terms) ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to edit these items.' ) . '</p>',
+		403 );
+}
 
 $messages = array();
 $messages['_item'] = array(
Index: src/wp-admin/edit.php
===================================================================
--- src/wp-admin/edit.php	(revision 31408)
+++ src/wp-admin/edit.php	(working copy)
@@ -26,8 +26,12 @@
 if ( ! $post_type_object )
 	wp_die( __( 'Invalid post type' ) );
 
-if ( ! current_user_can( $post_type_object->cap->edit_posts ) )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( ! current_user_can( $post_type_object->cap->edit_posts ) ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to edit these items.' ) . '</p>',
+		403 );
+}
 
 $wp_list_table = _get_list_table('WP_Posts_List_Table');
 $pagenum = $wp_list_table->get_pagenum();
Index: src/wp-admin/includes/bookmark.php
===================================================================
--- src/wp-admin/includes/bookmark.php	(revision 31408)
+++ src/wp-admin/includes/bookmark.php	(working copy)
@@ -26,8 +26,12 @@
  * @return int|WP_Error Value 0 or WP_Error on failure. The link ID on success.
  */
 function edit_link( $link_id = 0 ) {
-	if ( !current_user_can( 'manage_links' ) )
-		wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	if ( !current_user_can( 'manage_links' ) ) {
+		wp_die(
+			'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+			'<p>' . __( 'You are not allowed to edit links.' ) . '</p>',
+			403 );
+	}
 
 	$_POST['link_url'] = esc_html( $_POST['link_url'] );
 	$_POST['link_url'] = esc_url($_POST['link_url']);
Index: src/wp-admin/media-upload.php
===================================================================
--- src/wp-admin/media-upload.php	(revision 31408)
+++ src/wp-admin/media-upload.php	(working copy)
@@ -36,7 +36,10 @@
 }
 
 if ( ! empty( $_REQUEST['post_id'] ) && ! current_user_can( 'edit_post' , $_REQUEST['post_id'] ) ) {
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to edit this post.' ) . '</p>',
+		403 );
 }
 
 // Upload type: image, video, file, ..?
Index: src/wp-admin/nav-menus.php
===================================================================
--- src/wp-admin/nav-menus.php	(revision 31408)
+++ src/wp-admin/nav-menus.php	(working copy)
@@ -19,8 +19,12 @@
 	wp_die( __( 'Your theme does not support navigation menus or widgets.' ) );
 
 // Permissions Check
-if ( ! current_user_can('edit_theme_options') )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( ! current_user_can('edit_theme_options') ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to manage theme options.' ) . '</p>',
+		403 );
+}
 
 wp_enqueue_script( 'nav-menu' );
 
Index: src/wp-admin/network/site-users.php
===================================================================
--- src/wp-admin/network/site-users.php	(revision 31408)
+++ src/wp-admin/network/site-users.php	(working copy)
@@ -132,8 +132,12 @@
 					$user_id = (int) $user_id;
 
 					// If the user doesn't already belong to the blog, bail.
-					if ( !is_user_member_of_blog( $user_id ) )
-						wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+					if ( !is_user_member_of_blog( $user_id ) ) {
+						wp_die(
+							'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+							'<p>' . __( 'One of the selected users is not a member of this site.' ) . '</p>',
+							403 );
+					}
 
 					$user = get_userdata( $user_id );
 					$user->set_role( $_REQUEST['new_role'] );
Index: src/wp-admin/options.php
===================================================================
--- src/wp-admin/options.php	(revision 31408)
+++ src/wp-admin/options.php	(working copy)
@@ -44,8 +44,12 @@
 	$capability = apply_filters( "option_page_capability_{$option_page}", $capability );
 }
 
-if ( !current_user_can( $capability ) )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( !current_user_can( $capability ) ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to manage these options.' ) . '</p>',
+		403 );
+}
 
 // Handle admin email change requests
 if ( is_multisite() ) {
@@ -68,8 +72,12 @@
 	}
 }
 
-if ( is_multisite() && !is_super_admin() && 'update' != $action )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( is_multisite() && !is_super_admin() && 'update' != $action ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to edit options.' ) . '</p>',
+		403 );
+}
 
 $whitelist_options = array(
 	'general' => array( 'blogname', 'blogdescription', 'gmt_offset', 'date_format', 'time_format', 'start_of_week', 'timezone_string', 'WPLANG' ),
Index: src/wp-admin/post-new.php
===================================================================
--- src/wp-admin/post-new.php	(revision 31408)
+++ src/wp-admin/post-new.php	(working copy)
@@ -49,8 +49,12 @@
 
 $editing = true;
 
-if ( ! current_user_can( $post_type_object->cap->edit_posts ) || ! current_user_can( $post_type_object->cap->create_posts ) )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( ! current_user_can( $post_type_object->cap->edit_posts ) || ! current_user_can( $post_type_object->cap->create_posts ) ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to create these items.' ) . '</p>',
+		403 );
+}
 
 // Schedule auto-draft cleanup
 if ( ! wp_next_scheduled( 'wp_scheduled_auto_draft_delete' ) )
Index: src/wp-admin/press-this.php
===================================================================
--- src/wp-admin/press-this.php	(revision 31408)
+++ src/wp-admin/press-this.php	(working copy)
@@ -13,8 +13,12 @@
 
 header('Content-Type: ' . get_option('html_type') . '; charset=' . get_option('blog_charset'));
 
-if ( ! current_user_can( 'edit_posts' ) || ! current_user_can( get_post_type_object( 'post' )->cap->create_posts ) )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( ! current_user_can( 'edit_posts' ) || ! current_user_can( get_post_type_object( 'post' )->cap->create_posts ) ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to create posts.' ) . '</p>',
+		403 );
+}
 
 /**
  * Press It form handler.
Index: src/wp-admin/themes.php
===================================================================
--- src/wp-admin/themes.php	(revision 31408)
+++ src/wp-admin/themes.php	(working copy)
@@ -9,15 +9,29 @@
 /** WordPress Administration Bootstrap */
 require_once( dirname( __FILE__ ) . '/admin.php' );
 
-if ( !current_user_can('switch_themes') && !current_user_can('edit_theme_options') )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( !current_user_can('switch_themes') && !current_user_can('edit_theme_options') ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to manage themes.' ) . '</p>',
+		403 );
+}
 
 if ( current_user_can( 'switch_themes' ) && isset($_GET['action'] ) ) {
 	if ( 'activate' == $_GET['action'] ) {
 		check_admin_referer('switch-theme_' . $_GET['stylesheet']);
 		$theme = wp_get_theme( $_GET['stylesheet'] );
-		if ( ! $theme->exists() || ! $theme->is_allowed() )
-			wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+		if ( ! $theme->exists() ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+				'<p>' . __( 'This theme does not exist.' ) . '</p>',
+				403 );
+		}
+		if ( ! $theme->is_allowed() ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+				'<p>' . __( 'This theme is not allowed to be activated on this site.' ) . '</p>',
+				403 );
+		}
 		switch_theme( $theme->get_stylesheet() );
 		wp_redirect( admin_url('themes.php?activated=true') );
 		exit;
@@ -24,8 +38,18 @@
 	} elseif ( 'delete' == $_GET['action'] ) {
 		check_admin_referer('delete-theme_' . $_GET['stylesheet']);
 		$theme = wp_get_theme( $_GET['stylesheet'] );
-		if ( !current_user_can('delete_themes') || ! $theme->exists() )
-			wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+		if ( !current_user_can('delete_themes') ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+				'<p>' . __( 'You are not allowed to delete themes.' ) . '</p>',
+				403 );
+		}
+		if ( ! $theme->exists() ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+				'<p>' . __( 'This theme does not exist.' ) . '</p>',
+				403 );
+		}
 		$active = wp_get_theme();
 		if ( $active->get( 'Template' ) == $_GET['stylesheet'] ) {
 			wp_redirect( admin_url( 'themes.php?delete-active-child=true' ) );
Index: src/wp-admin/user-new.php
===================================================================
--- src/wp-admin/user-new.php	(revision 31408)
+++ src/wp-admin/user-new.php	(working copy)
@@ -10,10 +10,17 @@
 require_once( dirname( __FILE__ ) . '/admin.php' );
 
 if ( is_multisite() ) {
-	if ( ! current_user_can( 'create_users' ) && ! current_user_can( 'promote_users' ) )
-		wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	if ( ! current_user_can( 'create_users' ) && ! current_user_can( 'promote_users' ) ) {
+		wp_die(
+			'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+			'<p>' . __( 'You are not allowed to create users.' ) . '</p>',
+			403 );
+	}
 } elseif ( ! current_user_can( 'create_users' ) ) {
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to create users.' ) . '</p>',
+		403 );
 }
 
 if ( is_multisite() ) {
@@ -54,8 +61,12 @@
 		die();
 	}
 
-	if ( ! current_user_can('promote_user', $user_details->ID) )
-		wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	if ( ! current_user_can('promote_user', $user_details->ID) ) {
+		wp_die(
+			'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+			'<p>' . __( 'You are not allowed to add the user to this site.' ) . '</p>',
+			403 );
+	}
 
 	// Adding an existing user to this blog
 	$new_user_email = $user_details->user_email;
@@ -91,8 +102,12 @@
 } elseif ( isset($_REQUEST['action']) && 'createuser' == $_REQUEST['action'] ) {
 	check_admin_referer( 'create-user', '_wpnonce_create-user' );
 
-	if ( ! current_user_can('create_users') )
-		wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+	if ( ! current_user_can('create_users') ) {
+		wp_die(
+			'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+			'<p>' . __( 'You are not allowed to create users.' ) . '</p>',
+			403 );
+	}
 
 	if ( ! is_multisite() ) {
 		$user_id = edit_user();
Index: src/wp-admin/users.php
===================================================================
--- src/wp-admin/users.php	(revision 31408)
+++ src/wp-admin/users.php	(working copy)
@@ -9,8 +9,12 @@
 /** WordPress Administration Bootstrap */
 require_once( dirname( __FILE__ ) . '/admin.php' );
 
-if ( ! current_user_can( 'list_users' ) )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( ! current_user_can( 'list_users' ) ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to browse users.' ) . '</p>',
+		403 );
+}
 
 $wp_list_table = _get_list_table('WP_Users_List_Table');
 $pagenum = $wp_list_table->get_pagenum();
@@ -127,8 +131,12 @@
 		}
 
 		// If the user doesn't already belong to the blog, bail.
-		if ( is_multisite() && !is_user_member_of_blog( $id ) )
-			wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+		if ( is_multisite() && !is_user_member_of_blog( $id ) ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+				'<p>' . __( 'One of the selected users is not a member of this site.' ) . '</p>',
+				403 );
+		}
 
 		$user = get_userdata( $id );
 		$user->set_role($_REQUEST['new_role']);
Index: src/wp-admin/widgets.php
===================================================================
--- src/wp-admin/widgets.php	(revision 31408)
+++ src/wp-admin/widgets.php	(working copy)
@@ -12,8 +12,12 @@
 /** WordPress Administration Widgets API */
 require_once(ABSPATH . 'wp-admin/includes/widgets.php');
 
-if ( ! current_user_can('edit_theme_options') )
-	wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+if ( ! current_user_can('edit_theme_options') ) {
+	wp_die(
+		'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1> ' .
+		'<p>' . __( 'You are not allowed to manage widgets.' ) . '</p>',
+		403 );
+}
 
 $widgets_access = get_user_setting( 'widgets_access' );
 if ( isset($_GET['widgets-access']) ) {
