diff --git a/docs/en/technical.md b/docs/en/technical.md
index cb705f1..27bfbe4 100644
--- a/docs/en/technical.md
+++ b/docs/en/technical.md
@@ -28,5 +28,5 @@ This method is called when a pages are being copied between the main site or ano
 ### alternateAbsoluteLink
 This method modifies the absolute link to contain the valid subsite domain
 
-### alternatePreviewLink
+### updatePreviewLink
 This method modifies the preview link for the CMS.
diff --git a/javascript/LeftAndMain_Subsites.js b/javascript/LeftAndMain_Subsites.js
index b1541ba..8dd2b24 100644
--- a/javascript/LeftAndMain_Subsites.js
+++ b/javascript/LeftAndMain_Subsites.js
@@ -101,7 +101,7 @@
 
 			/**
 			 * Update links and forms with GET/POST SubsiteID param, so we remaing on the current subsite.
-			 * The initial link for the iframe comes from SiteTreeSubsites::alternatePreviewLink.
+			 * The initial link for the iframe comes from SiteTreeSubsites::updatePreviewLink.
 			 *
 			 * This is done so we can use the CMS domain for displaying previews so we prevent single-origin
 			 * violations and SSL cert problems that come up when iframing content from a different URL.
diff --git a/src/Extensions/LeftAndMainSubsites.php b/src/Extensions/LeftAndMainSubsites.php
index c3a57af..760623f 100644
--- a/src/Extensions/LeftAndMainSubsites.php
+++ b/src/Extensions/LeftAndMainSubsites.php
@@ -160,7 +160,7 @@ class LeftAndMainSubsites extends LeftAndMainExtension
             $output->push(ArrayData::create([
                 'CurrentState' => $currentState,
                 'ID' => $subsite->ID,
-                'Title' => Convert::raw2xml($subsite->Title)
+                'Title' => $subsite->Title,
             ]));
         }
 
diff --git a/src/Extensions/SiteTreeSubsites.php b/src/Extensions/SiteTreeSubsites.php
index e36bea5..488fef6 100644
--- a/src/Extensions/SiteTreeSubsites.php
+++ b/src/Extensions/SiteTreeSubsites.php
@@ -273,8 +273,10 @@ class SiteTreeSubsites extends DataExtension
      * - Is in a group which has access to the subsite this page belongs to
      * - Is in a group with edit permissions on the "main site"
      *
-     * @param null $member
-     * @return bool
+     * If there are no subsites configured yet, this logic is skipped.
+     *
+     * @param Member|null $member
+     * @return bool|null
      */
     public function canEdit($member = null)
     {
@@ -282,6 +284,11 @@ class SiteTreeSubsites extends DataExtension
             $member = Security::getCurrentUser();
         }
 
+        // Do not provide any input if there are no subsites configured
+        if (!Subsite::get()->exists()) {
+            return null;
+        }
+
         // Find the sites that this user has access to
         $goodSites = Subsite::accessible_sites('CMS_ACCESS_CMSMain', true, 'all', $member)->column('ID');
 
@@ -329,8 +336,8 @@ class SiteTreeSubsites extends DataExtension
     }
 
     /**
-     * @param null $member
-     * @return bool
+     * @param Member|null $member
+     * @return bool|null
      */
     public function canPublish($member = null)
     {
@@ -375,17 +382,31 @@ class SiteTreeSubsites extends DataExtension
 
     /**
      * Use the CMS domain for iframed CMS previews to prevent single-origin violations
-     * and SSL cert problems.
-     * @param null $action
+     * and SSL cert problems. Always set SubsiteID to avoid errors because a page doesn't
+     * exist on the CMS domain.
+     *
+     * @param string &$link
+     * @param string|null $action
+     * @return string
+     */
+    public function updatePreviewLink(&$link, $action = null)
+    {
+        $url = Director::absoluteURL($this->owner->Link($action));
+        $link = HTTP::setGetVar('SubsiteID', $this->owner->SubsiteID, $url);
+        return $link;
+    }
+
+    /**
+     * This function is marked as deprecated for removal in 5.0.0 in silverstripe/cms
+     * so now simply passes execution to where the functionality exists for backwards compatiblity.
+     *
+     * @param string|null $action
      * @return string
      */
     public function alternatePreviewLink($action = null)
     {
-        $url = Director::absoluteURL($this->owner->Link());
-        if ($this->owner->SubsiteID) {
-            $url = HTTP::setGetVar('SubsiteID', $this->owner->SubsiteID, $url);
-        }
-        return $url;
+        $link = '';
+        return $this->updatePreviewLink($link, $action);
     }
 
     /**