diff --git a/.upgrade.yml b/.upgrade.yml
index 0bfa949b..d59203ba 100644
--- a/.upgrade.yml
+++ b/.upgrade.yml
@@ -150,9 +150,12 @@ excludedPaths:
   - '*/_config/legacy.yml'
 warnings:
   methods:
-    'SilverStripe\CMS\Model\SiteTree::getIsAddedToStage()':
+    'SilverStripe\CMS\Model\SiteTree->getIsAddedToStage()':
       message: 'Moved to Versioned->isOnDraftOnly()'
-    'SilverStripe\CMS\Model\SiteTree::getIsModifiedOnStage()':
+      replacement: 'isOnDraftOnly'
+    'SilverStripe\CMS\Model\SiteTree->getIsModifiedOnStage()':
       message: 'Moved to Versioned->isModifiedOnDraft()'
-    'SilverStripe\CMS\Model\SiteTree::getExistsOnLive()':
+      replacement: 'isModifiedOnDraft'
+    'SilverStripe\CMS\Model\SiteTree->getExistsOnLive()':
       message: 'Removed in favour of isPublished()'
+      replacement: 'isPublished'
diff --git a/code/Model/SiteTree.php b/code/Model/SiteTree.php
index 82b8f595..a3815a8a 100755
--- a/code/Model/SiteTree.php
+++ b/code/Model/SiteTree.php
@@ -773,8 +773,8 @@ class SiteTree extends DataObject implements PermissionProvider, i18nEntityProvi
     public function InSection($sectionName)
     {
         $page = Director::get_current_page();
-        while ($page && $page->exists()) {
-            if ($sectionName == $page->URLSegment) {
+        while ($page instanceof SiteTree && $page->exists()) {
+            if ($sectionName === $page->URLSegment) {
                 return true;
             }
             $page = $page->Parent();
diff --git a/code/Model/VirtualPage.php b/code/Model/VirtualPage.php
index 7b70f49e..e4acf2ff 100644
--- a/code/Model/VirtualPage.php
+++ b/code/Model/VirtualPage.php
@@ -12,7 +12,6 @@ use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\ValidationResult;
 use SilverStripe\Security\Member;
 use SilverStripe\Versioned\Versioned;
-use SilverStripe\View\SSViewer;
 
 /**
  * Virtual Page creates an instance of a  page, with the same fields that the original page had, but readonly.
@@ -366,7 +365,11 @@ class VirtualPage extends Page
 
     public function CMSTreeClasses()
     {
-        return parent::CMSTreeClasses() . ' VirtualPage-' . $this->CopyContentFrom()->ClassName;
+        $parentClass = sprintf(
+            ' VirtualPage-%s',
+            Convert::raw2htmlid($this->CopyContentFrom()->ClassName)
+        );
+        return parent::CMSTreeClasses() . $parentClass;
     }
 
     /**