diff --git a/src/Controller/ChangesListController.php b/src/Controller/ChangesListController.php
old mode 100644
new mode 100755
index bc48fd5..ac6967b
--- a/src/Controller/ChangesListController.php
+++ b/src/Controller/ChangesListController.php
@@ -277,8 +277,8 @@ class ChangesListController extends ControllerBase {
         $row[] = $this->t('Changed');
       }
       // Set the author.
-      if (method_exists($entity, 'getOwner')) {
-        $row[] = ($name = $entity->getOwner()->get('name')->value) ? $name : '* ' . $this->t('No author') . ' *';
+      if (method_exists($entity, 'getOwner') && ($author = $entity->getOwner()) != NULL) {
+        $row[] = ($name = $author->get('name')->value) ? $name : '* ' . $this->t('No author') . ' *';
       }
       else {
         $row[] = '* ' . $this->t('No author') . ' *';
diff --git a/src/Controller/WorkspaceController.php b/src/Controller/WorkspaceController.php
old mode 100644
new mode 100755
index b161d3f..e4922bc
--- a/src/Controller/WorkspaceController.php
+++ b/src/Controller/WorkspaceController.php
@@ -55,15 +55,20 @@ class WorkspaceController extends ControllerBase {
    */
   public function addForm(WorkspaceTypeInterface $workspace_type) {
     $upstream_id = $this->workspaceSettings->get('upstream');
+
     if (!$upstream_id) {
-      $upstream_id = $this->getDefaultWorkspacePointer()->id();
+      if(!empty($this->getDefaultWorkspacePointer())) {
+        $upstream_id = $this->getDefaultWorkspacePointer()->id();
+      }
     }
+
     $workspace = Workspace::create([
       'type' => $workspace_type->id(),
       'upstream' => $upstream_id,
       'pull_replication_settings' => $this->workspaceSettings->get('pull_replication_settings', ''),
       'push_replication_settings' => $this->workspaceSettings->get('push_replication_settings', ''),
     ]);
+
     return $this->entityFormBuilder()->getForm($workspace);
   }
 
diff --git a/src/Entity/Form/WorkspaceDeleteForm.php b/src/Entity/Form/WorkspaceDeleteForm.php
old mode 100644
new mode 100755
index 5e9f086..2a49e68
--- a/src/Entity/Form/WorkspaceDeleteForm.php
+++ b/src/Entity/Form/WorkspaceDeleteForm.php
@@ -60,7 +60,7 @@ class WorkspaceDeleteForm extends ContentEntityConfirmFormBase {
     return new static(
       $container->get('workspace.manager'),
       $container->getParameter('workspace.default'),
-      $container->get('entity.manager'),
+      $container->get('entity_type.manager'),
       $container->get('entity.repository'),
       $container->get('entity_type.bundle.info'),
       $container->get('datetime.time')
diff --git a/src/Entity/Form/WorkspaceForm.php b/src/Entity/Form/WorkspaceForm.php
old mode 100644
new mode 100755
index c2ea741..8cd35b7
--- a/src/Entity/Form/WorkspaceForm.php
+++ b/src/Entity/Form/WorkspaceForm.php
@@ -5,12 +5,16 @@ namespace Drupal\workspace\Entity\Form;
 use Drupal\Core\Entity\ContentEntityForm;
 use Drupal\Core\Entity\EntityConstraintViolationListInterface;
 use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Entity\EntityTypeBundleInfo;
 use Drupal\Core\Entity\EntityTypeBundleInfoInterface;
+use Drupal\Core\Entity\EntityTypeManager;
+use Drupal\Core\Entity\EntityRepositoryInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Render\Markup;
 use Drupal\Core\Url;
 use Drupal\multiversion\Workspace\ConflictTrackerInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
+use Drupal\Component\Datetime\TimeInterface;
 
 /**
  * Form controller for the workspace edit forms.
@@ -31,19 +35,30 @@ class WorkspaceForm extends ContentEntityForm {
    */
   protected $entity;
 
+  /**
+   * The time service.
+   *
+   * @var \Drupal\Component\Datetime\TimeInterface
+   */
+  protected $time;
+
   /**
    * Constructs a ContentEntityForm object.
    *
-   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   * @param \Drupal\Core\Entity\EntityRepositoryInterface $entity_repository
+   *   The entity repository service.
+   * @param \Drupal\Core\Entity\EntityTypeBundleInfo $entity_type_bundle_info
+   *   The entity type bundle service.
    * @param ConflictTrackerInterface $conflict_tracker
    *   The conflict tracking service.
-   * @param \Drupal\Core\Entity\EntityTypeBundleInfoInterface $entity_type_bundle_info
+   * @param \Drupal\Component\Datetime\TimeInterface $time
+   *   The time service.
    *
    * @todo Add TimeInterface as parameter for constructor and use the value in
    * parent constructor starting with Drupal 8.4.0.
    */
-  public function __construct(EntityManagerInterface $entity_manager, ConflictTrackerInterface $conflict_tracker, EntityTypeBundleInfoInterface $entity_type_bundle_info = NULL) {
-    parent::__construct($entity_manager, $entity_type_bundle_info);
+  public function __construct(EntityRepositoryInterface $entity_repository, EntityTypeBundleInfo $entityTypeBundleInfo, ConflictTrackerInterface $conflict_tracker, TimeInterface $time) {
+    parent::__construct($entity_repository, $entityTypeBundleInfo, $time);
     $this->conflictTracker = $conflict_tracker;
   }
 
@@ -52,9 +67,10 @@ class WorkspaceForm extends ContentEntityForm {
    */
   public static function create(ContainerInterface $container) {
     return new static(
-      $container->get('entity.manager'),
+      $container->get('entity.repository'),
+      $container->get('entity_type.bundle.info'),
       $container->get('workspace.conflict_tracker'),
-      $container->get('entity_type.bundle.info')
+      $container->get('datetime.time')
     );
   }
 
@@ -179,7 +195,7 @@ class WorkspaceForm extends ContentEntityForm {
 
       if ($replication_status == TRUE) {
         // The replication succeeded, in addition to saving the workspace.
-        drupal_set_message($this->t('Workspace :source has been updated and changes were pushed to :target.', [
+        \Drupal::messenger()->addMessage($this->t('Workspace :source has been updated and changes were pushed to :target.', [
           ':source' => $workspace->label(),
           ':target' => $workspace->get('upstream')->entity->label(),
         ]), 'status');
@@ -212,11 +228,11 @@ class WorkspaceForm extends ContentEntityForm {
       // installed.
       if ($is_new) {
         $logger->notice('@type: added %info.', $context);
-        drupal_set_message($this->t('Workspace %info has been created.', $info));
+        \Drupal::messenger()->addMessage($this->t('Workspace %info has been created.', $info));
       }
       else {
         $logger->notice('@type: updated %info.', $context);
-        drupal_set_message($this->t('Workspace %info has been updated.', $info));
+        \Drupal::messenger()->addMessage($this->t('Workspace %info has been updated.', $info));
       }
 
       if ($workspace->id()) {
@@ -226,7 +242,7 @@ class WorkspaceForm extends ContentEntityForm {
         $form_state->setRedirectUrl($redirect);
       }
       else {
-        drupal_set_message($this->t('The workspace could not be saved.'), 'error');
+        \Drupal::messenger()->addMessage($this->t('The workspace could not be saved.'), 'error');
         $form_state->setRebuild();
       }
     }
diff --git a/src/Entity/Form/WorkspaceTypeForm.php b/src/Entity/Form/WorkspaceTypeForm.php
old mode 100644
new mode 100755
index 8074860..d1f8c44
--- a/src/Entity/Form/WorkspaceTypeForm.php
+++ b/src/Entity/Form/WorkspaceTypeForm.php
@@ -48,13 +48,13 @@ class WorkspaceTypeForm extends BundleEntityFormBase {
 
     switch ($status) {
       case SAVED_NEW:
-        drupal_set_message($this->t('Created the %label Workspace type.', [
+        $this->messenger()->addStatus($this->t('Created the %label Workspace type.', [
           '%label' => $workspace_type->label(),
         ]));
         break;
 
       default:
-        drupal_set_message($this->t('Saved the %label Workspace type.', [
+        $this->messenger()->addStatus($this->t('Saved the %label Workspace type.', [
           '%label' => $workspace_type->label(),
         ]));
     }
diff --git a/src/EventSubscriber/WorkbenchModerationSubscriber.php b/src/EventSubscriber/WorkbenchModerationSubscriber.php
old mode 100644
new mode 100755
index 9475220..2d3d57c
--- a/src/EventSubscriber/WorkbenchModerationSubscriber.php
+++ b/src/EventSubscriber/WorkbenchModerationSubscriber.php
@@ -55,9 +55,9 @@ class WorkbenchModerationSubscriber implements EventSubscriberInterface {
 
       // If there is no upstream to replicate to, abort.
       if (!$entity->get('upstream')->entity) {
-        drupal_set_message(t('The :source workspace does not have an upstream to replicate to!', [
+        \Drupal::messenger()->addError(t('The :source workspace does not have an upstream to replicate to!', [
           ':source' => $entity->label(),
-        ]), 'error');
+        ]));
 
         // @todo Should we revert the workspace to its previous state?
 
diff --git a/src/Form/ConfirmClearReplicationQueueForm.php b/src/Form/ConfirmClearReplicationQueueForm.php
old mode 100644
new mode 100755
index d945331..f69a0b7
--- a/src/Form/ConfirmClearReplicationQueueForm.php
+++ b/src/Form/ConfirmClearReplicationQueueForm.php
@@ -33,7 +33,7 @@ class ConfirmClearReplicationQueueForm extends ConfirmFormBase {
    */
   public static function create(ContainerInterface $container) {
     return new static(
-      $container->get('entity.manager')
+      $container->get('entity_type.manager')
     );
   }
 
diff --git a/src/Form/UpdateForm.php b/src/Form/UpdateForm.php
old mode 100644
new mode 100755
index ec431bd..0de2e50
--- a/src/Form/UpdateForm.php
+++ b/src/Form/UpdateForm.php
@@ -185,7 +185,7 @@ class UpdateForm extends ConfirmFormBase {
           ->getAll();
 
         if ($conflicts) {
-          drupal_set_message($this->t(
+          $this->messenger()->addError($this->t(
             '%workspace has been updated with content from %upstream, but there are <a href=":link">@count conflict(s) with the %target workspace</a>.',
             [
               '%upstream' => $upstream->label(),
@@ -194,10 +194,10 @@ class UpdateForm extends ConfirmFormBase {
               '@count' => count($conflicts),
               '%target' => $upstream->label(),
             ]
-          ), 'error');
+          ));
         }
         else {
-          drupal_set_message($this->t('An update of %workspace has been queued with content from %upstream.', ['%upstream' => $upstream->label(), '%workspace' => $active->label()]));
+          $this->messenger()->addStatus($this->t('An update of %workspace has been queued with content from %upstream.', ['%upstream' => $upstream->label(), '%workspace' => $active->label()]));
           if (\Drupal::moduleHandler()->moduleExists('deploy')) {
             $input = $form_state->getUserInput();
             if (!isset($input['_drupal_ajax'])) {
@@ -207,12 +207,12 @@ class UpdateForm extends ConfirmFormBase {
         }
       }
       else {
-        drupal_set_message($this->t('Error updating %workspace from %upstream.', ['%upstream' => $upstream->label(), '%workspace' => $active->label()]), 'error');
+        $this->messenger()->addError($this->t('Error updating %workspace from %upstream.', ['%upstream' => $upstream->label(), '%workspace' => $active->label()]));
       }
     }
     catch (\Exception $e) {
       watchdog_exception('Workspace', $e);
-      drupal_set_message($e->getMessage(), 'error');
+      $this->messenger()->addError($e->getMessage());
     }
   }
 
diff --git a/src/Form/WorkspaceActivateFormBase.php b/src/Form/WorkspaceActivateFormBase.php
old mode 100644
new mode 100755
index caa5cec..8158c65
--- a/src/Form/WorkspaceActivateFormBase.php
+++ b/src/Form/WorkspaceActivateFormBase.php
@@ -75,7 +75,7 @@ abstract class WorkspaceActivateFormBase extends FormBase {
     }
     catch(\Exception $e) {
       watchdog_exception('Workspace', $e);
-      drupal_set_message($e->getMessage(), 'error');
+      $this->messenger()->addError($e->getMessage());
     }
   }
 
diff --git a/src/InternalReplicator.php b/src/InternalReplicator.php
old mode 100644
new mode 100755
index 1c85991..081acd3
--- a/src/InternalReplicator.php
+++ b/src/InternalReplicator.php
@@ -114,7 +114,7 @@ class InternalReplicator implements ReplicatorInterface {
     }
     catch (\Throwable $e) {
       $this->logger->error('%type: @message in %function (line %line of %file).', Error::decodeException($e));
-      drupal_set_message($e->getMessage(), 'error');
+      \Drupal::messenger()->addError($e->getMessage());
     }
     // Fetch the site time.
     $start_time = new \DateTime();
diff --git a/src/Plugin/Block/WorkspaceBlock.php b/src/Plugin/Block/WorkspaceBlock.php
old mode 100644
new mode 100755
index e2274ad..65e47e9
--- a/src/Plugin/Block/WorkspaceBlock.php
+++ b/src/Plugin/Block/WorkspaceBlock.php
@@ -7,6 +7,7 @@ use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\multiversion\Workspace\WorkspaceManagerInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
+use Drupal\workspace\Toolbar;
 
 /**
  * @Block(
@@ -54,7 +55,7 @@ class WorkspaceBlock extends BlockBase implements ContainerFactoryPluginInterfac
   public function build() {
     $build = [
       // @todo the block depending on the toolbar is obscure; find a better way to generate this form
-      '#pre_render' => ['workspace.toolbar:preRenderWorkspaceSwitcherForms'],
+      '#pre_render' => [Toolbar::class, 'preRenderWorkspaceSwitcherForms'],
       // This wil get filled in via pre-render.
       'workspace_forms' => [],
       '#attached' => [
diff --git a/src/Plugin/EntityReferenceSelection/WorkspacePointerSelection.php b/src/Plugin/EntityReferenceSelection/WorkspacePointerSelection.php
old mode 100644
new mode 100755
index 6aedb85..099a0a9
--- a/src/Plugin/EntityReferenceSelection/WorkspacePointerSelection.php
+++ b/src/Plugin/EntityReferenceSelection/WorkspacePointerSelection.php
@@ -51,8 +51,9 @@ class WorkspacePointerSelection extends DefaultSelection {
     }
 
     $options = [];
-    $entities = $this->entityManager->getStorage($target_type)->loadMultiple($result);
+    $entities = $this->entityTypeManager->getStorage($target_type)->loadMultiple($result);
     foreach ($entities as $entity_id => $entity) {
+      //var_dump($this);
       /** @var WorkspaceInterface $workspace */
       if ($workspace = $entity->getWorkspace()) {
         if (!$workspace->isPublished() || $workspace->getQueuedForDelete()) {
@@ -60,7 +61,7 @@ class WorkspacePointerSelection extends DefaultSelection {
         }
       }
       $bundle = $entity->bundle();
-      $options[$bundle][$entity_id] = Html::escape($this->entityManager->getTranslationFromContext($entity)->label());
+      $options[$bundle][$entity_id] = Html::escape($this->entityRepository->getTranslationFromContext($entity)->label());
     }
 
     return $options;
diff --git a/src/Toolbar.php b/src/Toolbar.php
old mode 100644
new mode 100755
index 5facf4c..11cfc00
--- a/src/Toolbar.php
+++ b/src/Toolbar.php
@@ -132,7 +132,7 @@ class Toolbar {
 
     $items['workspace_switcher']['tray'] = [
       '#heading' => $this->t('Switch to workspace'),
-      '#pre_render' => ['workspace.toolbar:preRenderWorkspaceSwitcherForms'],
+      '#pre_render' => '::preRenderWorkspaceSwitcherForms',
       // This wil get filled in via pre-render.
       'workspace_forms' => [],
       'create_link' => $create_link,
diff --git a/src/WorkspaceListBuilder.php b/src/WorkspaceListBuilder.php
old mode 100644
new mode 100755
index a0df3ce..aaafdba
--- a/src/WorkspaceListBuilder.php
+++ b/src/WorkspaceListBuilder.php
@@ -22,7 +22,7 @@ class WorkspaceListBuilder extends EntityListBuilder {
   public static function createInstance(ContainerInterface $container, EntityTypeInterface $entity_type) {
     return new static(
       $entity_type,
-      $container->get('entity.manager')->getStorage($entity_type->id()),
+      $container->get('entity_type.manager')->getStorage($entity_type->id()),
       $container->get('workspace.manager')
     );
   }
diff --git a/tests/src/Functional/ReplicationSettingsTest.php b/tests/src/Functional/ReplicationSettingsTest.php
old mode 100644
new mode 100755
index afd2260..86fc86c
--- a/tests/src/Functional/ReplicationSettingsTest.php
+++ b/tests/src/Functional/ReplicationSettingsTest.php
@@ -2,7 +2,7 @@
 
 namespace Drupal\Tests\workspace\Functional;
 
-use Drupal\simpletest\BlockCreationTrait;
+use Drupal\Tests\block\Traits\BlockCreationTrait;
 use Drupal\Tests\BrowserTestBase;
 
 /**
diff --git a/tests/src/Functional/ReplicatorAliasTest.php b/tests/src/Functional/ReplicatorAliasTest.php
old mode 100644
new mode 100755
index dc958b7..f6eb8e8
--- a/tests/src/Functional/ReplicatorAliasTest.php
+++ b/tests/src/Functional/ReplicatorAliasTest.php
@@ -2,11 +2,11 @@
 
 namespace Drupal\Tests\workspace\Functional;
 
+use Drupal\Tests\pathauto\Functional\PathautoTestHelperTrait;
 use Drupal\Tests\block\Traits\BlockCreationTrait;
 use Drupal\replication\ReplicationTask\ReplicationTask;
 use Drupal\Tests\BrowserTestBase;
 use Drupal\taxonomy\Entity\Vocabulary;
-use Drupal\Tests\pathauto\Functional\PathautoTestHelperTrait;
 
 /**
  * Test the workspace entity with EventSubscriber alias change.
@@ -90,7 +90,7 @@ class ReplicatorAliasTest extends BrowserTestBase {
     $this->setupWorkspaceSwitcherBlock();
 
     $this->entityTypeManager = \Drupal::entityTypeManager();
-    $this->aliasManager = \Drupal::service('path.alias_manager');
+    $this->aliasManager = \Drupal::service('path_alias.manager');
     $this->pathAutoGenerator = \Drupal::service('pathauto.generator');
   }
 
diff --git a/tests/src/Functional/WorkspaceBypassTest.php b/tests/src/Functional/WorkspaceBypassTest.php
old mode 100644
new mode 100755
index ad46ee9..2059961
--- a/tests/src/Functional/WorkspaceBypassTest.php
+++ b/tests/src/Functional/WorkspaceBypassTest.php
@@ -2,7 +2,7 @@
 
 namespace Drupal\Tests\workspace\Functional;
 
-use Drupal\simpletest\BlockCreationTrait;
+use Drupal\Tests\block\Traits\BlockCreationTrait;
 use Drupal\Tests\BrowserTestBase;
 
 /**
diff --git a/tests/src/Functional/WorkspaceSwitcherTest.php b/tests/src/Functional/WorkspaceSwitcherTest.php
old mode 100644
new mode 100755
index 42e13d2..6e7dc6e
--- a/tests/src/Functional/WorkspaceSwitcherTest.php
+++ b/tests/src/Functional/WorkspaceSwitcherTest.php
@@ -2,7 +2,7 @@
 
 namespace Drupal\Tests\workspace\Functional;
 
-use Drupal\simpletest\BlockCreationTrait;
+use Drupal\Tests\block\Traits\BlockCreationTrait;
 use Drupal\Tests\BrowserTestBase;
 
 /**
diff --git a/workspace.info.yml b/workspace.info.yml
old mode 100644
new mode 100755
index ed0cba4..dde2bed
--- a/workspace.info.yml
+++ b/workspace.info.yml
@@ -1,11 +1,11 @@
 name: Workspace
 type: module
 description: Provides the ability to have multiple workspaces on a single site to facilitate things like full-site preview and content staging.
-core: 8.x
+core_version_requirement: ^8 || ^9
 dependencies:
   - drupal:options
   - drupal:datetime
   - replication:replication
 
 test_dependencies:
-  - pathauto:pathauto
+  - pathauto:pathauto
\ No newline at end of file
diff --git a/workspace.module b/workspace.module
old mode 100644
new mode 100755
index a2be16f..3f10fa9
--- a/workspace.module
+++ b/workspace.module
@@ -1,5 +1,6 @@
 <?php
 
+use Drupal\Core\Entity\EntityTypeInterface;
 use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\FieldableEntityInterface;
@@ -57,7 +58,7 @@ function workspace_entity_type_build(array &$entity_types) {
 /**
  * Implements hook_entity_base_field_info().
  */
-function workspace_entity_base_field_info(\Drupal\Core\Entity\EntityTypeInterface $entity_type) {
+function workspace_entity_base_field_info(EntityTypeInterface $entity_type) {
   return \Drupal::service('workspace.entity_type_info')->entityBaseFieldInfo($entity_type);
 }
 
@@ -84,7 +85,7 @@ function workspace_workspace_insert(WorkspaceInterface $workspace) {
 }
 
 function workspace_pointer_allowed_values(FieldStorageDefinitionInterface $definition, FieldableEntityInterface $entity = NULL, &$cacheable) {
-  return \Drupal\workspace\Entity\Replication::getPointerAllowedValues($definition, $entity, $cacheable);
+  return Replication::getPointerAllowedValues($definition, $entity, $cacheable);
 }
 
 /**