--- taxonomy.module.org	2006-01-11 16:01:30.000000000 +0100
+++ taxonomy.module	2006-01-11 16:00:34.000000000 +0100
@@ -1013,7 +1013,11 @@
       taxonomy_node_save($node->nid, $node->taxonomy);
       break;
     case 'update':
-      taxonomy_node_save($node->nid, $node->taxonomy);
+      // taxonomy field is not set if we choose 'set active'.
+      // As terms are not yet versioned, we do not need to do anything here.
+      if (isset($node->taxonomy)) {
+        taxonomy_node_save($node->nid, $node->taxonomy);
+      }
       break;
     case 'delete':
       taxonomy_node_delete($node->nid);