diff --git a/boards/static/js/thread_update.js b/boards/static/js/thread_update.js
--- a/boards/static/js/thread_update.js
+++ b/boards/static/js/thread_update.js
@@ -441,8 +441,12 @@ function updateNodeAttr(oldNode, newNode
                     showAsErrors(form, gettext('Sending message...'));
                 },
                 success: updateOnPost,
-                error: function() {
-                    showAsErrors(form, gettext('Server error!'));
+                error: function(xhr, textStatus, errorString) {
+                    var errorText = gettext('Server error: ') + textStatus;
+                    if (errorString) {
+                        errorText += ' / ' + errorString;
+                    }
+                    showAsErrors(form, errorText);
                 },
                 url: '/api/add_post/' + threadId + '/',
                 timeout: POST_AJAX_TIMEOUT