diff --git a/wp-includes/classes.php b/wp-includes/classes.php
index 7cf3eed201..3bf318db61 100644
--- a/wp-includes/classes.php
+++ b/wp-includes/classes.php
@@ -764,7 +764,7 @@ class WP_Ajax_Response {
 				$response .= "<wp_error_data code='$code'$class>";
 
 				if ( is_scalar($error_data) ) {
-					$response .= "<![CDATA[$v]]>";
+					$response .= "<![CDATA[$error_data]]>";
 				} elseif ( is_array($error_data) ) {
 					foreach ( $error_data as $k => $v )
 						$response .= "<$k><![CDATA[$v]]></$k>";
diff --git a/wp-includes/taxonomy.php b/wp-includes/taxonomy.php
index 41d1035d94..035567c0e7 100644
--- a/wp-includes/taxonomy.php
+++ b/wp-includes/taxonomy.php
@@ -1153,14 +1153,14 @@ function wp_insert_term( $term, $taxonomy, $args = array() ) {
 
 	if ( ! $term_id = is_term($slug) ) {
 		if ( false === $wpdb->insert( $wpdb->terms, compact( 'name', 'slug', 'term_group' ) ) )
-			return new WP_Error('db_insert_error', __('Could not insert term into the database'));
+			return new WP_Error('db_insert_error', __('Could not insert term into the database'), $wpdb->last_error);
 		$term_id = (int) $wpdb->insert_id;
 	} else if ( is_taxonomy_hierarchical($taxonomy) && !empty($parent) ) {
 		// If the taxonomy supports hierarchy and the term has a parent, make the slug unique
 		// by incorporating parent slugs.
 		$slug = wp_unique_term_slug($slug, (object) $args);
 		if ( false === $wpdb->insert( $wpdb->terms, compact( 'name', 'slug', 'term_group' ) ) )
-			return new WP_Error('db_insert_error', __('Could not insert term into the database'));
+			return new WP_Error('db_insert_error', __('Could not insert term into the database'), $wpdb->last_error);
 		$term_id = (int) $wpdb->insert_id;
 	}
 
diff --git a/wp-includes/wp-db.php b/wp-includes/wp-db.php
index f52d286c50..216c9cf027 100644
--- a/wp-includes/wp-db.php
+++ b/wp-includes/wp-db.php
@@ -18,6 +18,7 @@ class wpdb {
 
 	var $show_errors = false;
 	var $suppress_errors = false;
+	var $last_error = '';
 	var $num_queries = 0;
 	var $last_query;
 	var $col_info;
@@ -278,7 +279,7 @@ class wpdb {
 			$this->queries[] = array( $query, $this->timer_stop(), $this->get_caller() );
 
 		// If there is an error then take note of it..
-		if ( mysql_error($this->dbh) ) {
+		if ( $this->last_error = mysql_error($this->dbh) ) {
 			$this->print_error();
 			return false;
 		}