Index: upgrade.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/db/upgrade.php,v
retrieving revision 1.418
diff -u -r1.418 upgrade.php
--- upgrade.php	25 May 2010 18:25:50 -0000	1.418
+++ upgrade.php	26 May 2010 18:22:15 -0000
@@ -1962,22 +1962,25 @@
         );
         $stickyblocks = $DB->get_recordset('block_pinned_old');
         foreach ($stickyblocks as $stickyblock) {
-            $newblock = new object();
-            $newblock->blockname = $blocks[$stickyblock->blockid]->name;
-            $newblock->contextid = $syscontext->id;
-            $newblock->showinsubcontexts = 1;
-            switch ($stickyblock->pagetype) {
-                case 'course-view':
-                    $newblock->pagetypepattern = 'course-view-*';
-                    break;
-                default:
-                    $newblock->pagetypepattern = $stickyblock->pagetype;
-            }
-            $newblock->defaultregion = $newregions[$stickyblock->position];
-            $newblock->defaultweight = $stickyblock->weight;
-            $newblock->configdata = $stickyblock->configdata;
-            $newblock->visible = 1;
-            $DB->insert_record('block_instances', $newblock);
+            // Only if the block exists (avoid orphaned sticky blocks)
+            if (isset($blocks[$stickyblock->blockid]) and !empty($blocks[$stickyblock->blockid]->name)) {
+                $newblock = new object();
+                $newblock->blockname = $blocks[$stickyblock->blockid]->name;
+                $newblock->contextid = $syscontext->id;
+                $newblock->showinsubcontexts = 1;
+                switch ($stickyblock->pagetype) {
+                    case 'course-view':
+                        $newblock->pagetypepattern = 'course-view-*';
+                        break;
+                    default:
+                        $newblock->pagetypepattern = $stickyblock->pagetype;
+                }
+                $newblock->defaultregion = $newregions[$stickyblock->position];
+                $newblock->defaultweight = $stickyblock->weight;
+                $newblock->configdata = $stickyblock->configdata;
+                $newblock->visible = 1;
+                $DB->insert_record('block_instances', $newblock);
+            }
         }
 
     /// Main savepoint reached