diff --git a/admin/code/LeftAndMain.php b/admin/code/LeftAndMain.php
index 3042ed4fb..8ea523846 100644
--- a/admin/code/LeftAndMain.php
+++ b/admin/code/LeftAndMain.php
@@ -942,6 +942,7 @@ class LeftAndMain extends Controller implements PermissionProvider {
 			if($id === "") continue; // $id may be a blank string, which is invalid and should be skipped over
 
 			$record = $this->getRecord($id);
+			if(!$record) continue; // In case a page is no longer available
 			$recordController = ($this->stat('tree_class') == 'SiteTree') 
 				?  singleton('CMSPageEditController') 
 				: $this;
diff --git a/admin/tests/LeftAndMainTest.php b/admin/tests/LeftAndMainTest.php
index 9f727eb37..b7a1b807e 100644
--- a/admin/tests/LeftAndMainTest.php
+++ b/admin/tests/LeftAndMainTest.php
@@ -196,6 +196,52 @@ class LeftAndMainTest extends FunctionalTest {
 		
 		$this->session()->inst_set('loggedInAs', null);
 	}
+
+	/**
+	 * Test {@see LeftAndMain::updatetreenodes}
+	 */
+	public function testUpdateTreeNodes() {
+		$page1 = $this->objFromFixture('LeftAndMainTest_Object', 'page1');
+		$page2 = $this->objFromFixture('LeftAndMainTest_Object', 'page2');
+		$page3 = $this->objFromFixture('LeftAndMainTest_Object', 'page3');
+		$page31 = $this->objFromFixture('LeftAndMainTest_Object', 'page31');
+		$page32 = $this->objFromFixture('LeftAndMainTest_Object', 'page32');
+		$this->logInWithPermission('ADMIN');
+
+		// Check page
+		$result = $this->get('LeftAndMainTest_Controller/updatetreenodes?ids='.$page1->ID);
+		$this->assertEquals(200, $result->getStatusCode());
+		$this->assertEquals('text/json', $result->getHeader('Content-Type'));
+		$data = json_decode($result->getBody(), true);
+		$pageData = $data[$page1->ID];
+		$this->assertEquals(0, $pageData['ParentID']);
+		$this->assertEquals($page2->ID, $pageData['NextID']);
+		$this->assertEmpty($pageData['PrevID']);
+
+		// check subpage
+		$result = $this->get('LeftAndMainTest_Controller/updatetreenodes?ids='.$page31->ID);
+		$this->assertEquals(200, $result->getStatusCode());
+		$this->assertEquals('text/json', $result->getHeader('Content-Type'));
+		$data = json_decode($result->getBody(), true);
+		$pageData = $data[$page31->ID];
+		$this->assertEquals($page3->ID, $pageData['ParentID']);
+		$this->assertEquals($page32->ID, $pageData['NextID']);
+		$this->assertEmpty($pageData['PrevID']);
+
+		// Multiple pages
+		$result = $this->get('LeftAndMainTest_Controller/updatetreenodes?ids='.$page1->ID.','.$page2->ID);
+		$this->assertEquals(200, $result->getStatusCode());
+		$this->assertEquals('text/json', $result->getHeader('Content-Type'));
+		$data = json_decode($result->getBody(), true);
+		$this->assertEquals(2, count($data));
+
+		// Invalid IDs
+		$result = $this->get('LeftAndMainTest_Controller/updatetreenodes?ids=-3');
+		$this->assertEquals(200, $result->getStatusCode());
+		$this->assertEquals('text/json', $result->getHeader('Content-Type'));
+		$data = json_decode($result->getBody(), true);
+		$this->assertEquals(0, count($data));
+	}
 }
 
 /**
@@ -224,4 +270,6 @@ class LeftAndMainTest_Object extends DataObject implements TestOnly {
 		'Hierarchy'
 	);
 	
+	public function CMSTreeClasses() {}
+
 }
diff --git a/admin/tests/LeftAndMainTest.yml b/admin/tests/LeftAndMainTest.yml
index 77df56dde..4aa7534da 100644
--- a/admin/tests/LeftAndMainTest.yml
+++ b/admin/tests/LeftAndMainTest.yml
@@ -1,65 +1,94 @@
 LeftAndMainTest_Object:
    page1:
       Title: Page 1
+      Sort: 1
    page2:
       Title: Page 2
+      Sort: 2
    page3:
       Title: Page 3
+      Sort: 3
    page31:
       Title: Page 3.1
       Parent: =>LeftAndMainTest_Object.page3
+      Sort: 1
    page32:
       Title: Page 3.2
       Parent: =>LeftAndMainTest_Object.page3
+      Sort: 2
    page4:
       Title: Page 4
+      Sort: 4
    page5:
       Title: Page 5
+      Sort: 5
    page6:
       Title: Page 6
+      Sort: 6
    page7:
       Title: Page 7
+      Sort: 7
    page8:
       Title: Page 8
+      Sort: 8
    page9:
       Title: Page 9
+      Sort: 9
    page10:
       Title: Page 10
+      Sort: 10
    page11:
       Title: Page 11
+      Sort: 11
    page12:
       Title: Page 12
+      Sort: 12
    page13:
       Title: Page 13
+      Sort: 13
    page14:
       Title: Page 14
+      Sort: 14
    page15:
       Title: Page 15
+      Sort: 15
    page16:
       Title: Page 16
+      Sort: 16
    page17:
       Title: Page 17
+      Sort: 17
    page18:
       Title: Page 18
+      Sort: 18
    page19:
       Title: Page 19
+      Sort: 19
    page20:
       Title: Page 20
+      Sort: 20
    page21:
       Title: Page 21
+      Sort: 21
    page22:
       Title: Page 22
+      Sort: 22
    page23:
       Title: Page 23
+      Sort: 23
    page24:
       Title: Page 24
+      Sort: 24
    page25:
       Title: Page 25
+      Sort: 25
    page26:
       Title: Page 26
+      Sort: 26
    home:
       Title: Home
       URLSegment: home
+      Sort: 0
 Group:
    admin:
       Title: Administrators