Index: upgrades.php
===================================================================
--- upgrades.php	(revision 14103)
+++ upgrades.php	(working copy)
@@ -227,11 +227,13 @@
 				'<inp:topic _field="link" _Template="inbulletin/post_list"' => '<inp2:bb_TopicLink template="__default__"',
 			);
 
-			foreach ($replacements as $old_tag => $new_tag) {
-				$sql = 'UPDATE '.TABLE_PREFIX.'EmailMessage
-						SET Template = REPLACE(Template, '.$this->Conn->qstr($old_tag).', '.$this->Conn->qstr($new_tag).')
-						WHERE EventId IN ('.$event_ids.')';
-				$this->Conn->Query($sql);
+			if ($event_ids) {
+				foreach ($replacements as $old_tag => $new_tag) {
+					$sql = 'UPDATE '.TABLE_PREFIX.'EmailMessage
+							SET Template = REPLACE(Template, '.$this->Conn->qstr($old_tag).', '.$this->Conn->qstr($new_tag).')
+							WHERE EventId IN ('.$event_ids.')';
+					$this->Conn->Query($sql);
+				}
 			}
 
 			if ($mode == 'after') {