diff --git a/core/lib/Drupal/Core/TempStore/PrivateTempStore.php b/core/lib/Drupal/Core/TempStore/PrivateTempStore.php
index 83bcd80afe..714021fd30 100644
--- a/core/lib/Drupal/Core/TempStore/PrivateTempStore.php
+++ b/core/lib/Drupal/Core/TempStore/PrivateTempStore.php
@@ -118,6 +118,18 @@ public function get($key) {
    *   Thrown when a lock for the backend storage could not be acquired.
    */
   public function set($key, $value) {
+    if ($this->currentUser->isAnonymous()) {
+      // Ensure that an anonymous user has a session created for them, as
+      // otherwise subsequent page loads will not be able to retrieve their
+      // tempstore data. Note this has to be done before the key is created as
+      // the owner is used in key creation.
+      $this->startSession();
+      $session = $this->requestStack->getCurrentRequest()->getSession();
+      if (!$session->has('core.tempstore.private.owner')) {
+        $session->set('core.tempstore.private.owner', Crypt::randomBytesBase64());
+      }
+    }
+
     $key = $this->createkey($key);
     if (!$this->lockBackend->acquire($key)) {
       $this->lockBackend->wait($key);
@@ -210,14 +222,9 @@ protected function createkey($key) {
   protected function getOwner() {
     $owner = $this->currentUser->id();
     if ($this->currentUser->isAnonymous()) {
-      // Ensure that an anonymous user has a session created for them, as
-      // otherwise subsequent page loads will not be able to retrieve their
-      // tempstore data.
+      // Check to see if an owner key exists in the session.
       $this->startSession();
       $session = $this->requestStack->getCurrentRequest()->getSession();
-      if (!$session->has('core.tempstore.private.owner')) {
-        $session->set('core.tempstore.private.owner', Crypt::randomBytesBase64());
-      }
       $owner = $session->get('core.tempstore.private.owner');
     }
     return $owner;
diff --git a/core/lib/Drupal/Core/TempStore/SharedTempStore.php b/core/lib/Drupal/Core/TempStore/SharedTempStore.php
index c131a80fd2..064ae1c1b2 100644
--- a/core/lib/Drupal/Core/TempStore/SharedTempStore.php
+++ b/core/lib/Drupal/Core/TempStore/SharedTempStore.php
@@ -147,7 +147,11 @@ public function setIfNotExists($key, $value) {
       'data' => $value,
       'updated' => (int) $this->requestStack->getMasterRequest()->server->get('REQUEST_TIME'),
     ];
-    return $this->storage->setWithExpireIfNotExists($key, $value, $this->expire);
+    $set = $this->storage->setWithExpireIfNotExists($key, $value, $this->expire);
+    if ($set) {
+      $this->ensureAnonymousSession();
+    }
+    return $set;
   }
 
   /**
@@ -205,6 +209,7 @@ public function set($key, $value) {
       'data' => $value,
       'updated' => (int) $this->requestStack->getMasterRequest()->server->get('REQUEST_TIME'),
     ];
+    $this->ensureAnonymousSession();
     $this->storage->setWithExpire($key, $value, $this->expire);
     $this->lockBackend->release($key);
   }
@@ -276,4 +281,15 @@ public function deleteIfOwner($key) {
     return FALSE;
   }
 
+  /**
+   * Stores the owner in session if the user is anonymous.
+   *
+   * This method should be called when a value is set.
+   */
+  protected function ensureAnonymousSession() {
+    if (\Drupal::currentUser()->isAnonymous()) {
+      $this->requestStack->getCurrentRequest()->getSession()->set('core.tempstore.shared.owner', $this->owner);
+    }
+  }
+
 }
diff --git a/core/lib/Drupal/Core/TempStore/SharedTempStoreFactory.php b/core/lib/Drupal/Core/TempStore/SharedTempStoreFactory.php
index a1a9e46319..438e8beb57 100644
--- a/core/lib/Drupal/Core/TempStore/SharedTempStoreFactory.php
+++ b/core/lib/Drupal/Core/TempStore/SharedTempStoreFactory.php
@@ -88,9 +88,8 @@ public function get($collection, $owner = NULL) {
           $session = \Drupal::service('session');
           $this->requestStack->getCurrentRequest()->setSession($session);
           $session->start();
-          $session->set('core.tempstore.shared.owner', Crypt::randomBytesBase64());
         }
-        $owner = $this->requestStack->getCurrentRequest()->getSession()->get('core.tempstore.shared.owner');
+        $owner = $this->requestStack->getCurrentRequest()->getSession()->get('core.tempstore.shared.owner', Crypt::randomBytesBase64());
       }
     }