diff --git a/.gitignore b/.gitignore
index eaa2b07..78dfeb5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -40,6 +40,7 @@ tests/wordpress
 Thumbs.db
 /tests/compatibility/*.txt
 .DS_Store
+.vscode
 
 inc/sandbox.inc
 *.sh
diff --git a/src/Plugin.php b/src/Plugin.php
index 3d531a6..65136da 100644
--- a/src/Plugin.php
+++ b/src/Plugin.php
@@ -8,6 +8,10 @@ class Plugin {
 	// ElasticPrtess loads its features at plugins_loaded:10.
 	const INIT_PRIORITY = 11;
 
+	// Before ElasticPress 5.0.0, the Dashboard sync was run over AJAX.
+	// After ElasticPress 5.0.0, the Dashboard sync is run over the REST API.
+	const DASHBOARD_SYNC_API_CHANGE_V1 = '5.0.0';
+
 	public static function init() {
 		add_action( 'plugins_loaded', function () {
 			if ( ! defined( 'EP_VERSION' ) || version_compare( EP_VERSION, '3.0.0', '<' ) ) {
@@ -18,6 +22,8 @@ public static function init() {
 				return;
 			}
 
+			$elasticPressVersion  = EP_VERSION;
+
 			$activeLanguagesData  = apply_filters( 'wpml_active_languages', [] );
 			$activeLanguages      = array_keys( $activeLanguagesData );
 			$defaultLanguage      = apply_filters( 'wpml_default_language', '' );
@@ -37,6 +43,26 @@ public static function init() {
 			);
 			$indicesManager->addHooks();
 
+			$syncDashboard = version_compare( $elasticPressVersion, self::DASHBOARD_SYNC_API_CHANGE_V1, '<' )
+				? new Sync\DashboardAjax(
+						$indexables,
+						$indicesManager,
+						new Manager\DashboardStatus(
+							$activeLanguages
+						),
+						$activeLanguages,
+						$defaultLanguage
+					)
+				: new Sync\DashboardRest(
+						$indexables,
+						$indicesManager,
+						new Manager\DashboardStatus(
+							$activeLanguages
+						),
+						$activeLanguages,
+						$defaultLanguage
+					);
+
 			$feature = new Feature(
 				new Field\Search(
 					$elasticsearchVersion,
@@ -50,20 +76,13 @@ public static function init() {
 					$defaultLanguage,
 					$currentLanguage
 				),
-				new Sync\Dashboard(
-					$indexables,
-					$indicesManager,
-					new Manager\DashboardStatus(
-						$activeLanguages
-					),
-					$activeLanguages,
-					$defaultLanguage
-				),
+				$syncDashboard,
 				new Sync\Singular(
 					$indexables,
 					$indicesManager,
 					$activeLanguages,
-					$defaultLanguage
+					$defaultLanguage,
+					$elasticPressVersion
 				),
 				new Sync\CLI(
 					$indexables,
diff --git a/src/Sync/Dashboard.php b/src/Sync/Dashboard.php
index 5659411..70a68e5 100644
--- a/src/Sync/Dashboard.php
+++ b/src/Sync/Dashboard.php
@@ -11,7 +11,7 @@
 
 use WPML\ElasticPress\Traits\ManageIndexables;
 
-class Dashboard {
+abstract class Dashboard {
 
 	use ManageIndexables;
 
@@ -19,13 +19,13 @@ class Dashboard {
 	private $indexables;
 
 	/** @var Indices */
-	private $indicesManager;
+	protected $indicesManager;
 
 	/** @var DashboardStatus */
-	private $status;
+	protected $status;
 
 	/** @var array */
-	private $activeLanguages;
+	protected $activeLanguages;
 
 	/** @var string */
 	private $defaultLanguage;
@@ -33,6 +33,9 @@ class Dashboard {
 	/** @var string */
 	private $currentLanguage = '';
 
+	/** @var array */
+	private $fullIndexArgs = [];
+
 	/**
 	 * @param Indexables      $indexables
 	 * @param Indices         $indicesManager
@@ -54,20 +57,30 @@ public function __construct(
 		$this->defaultLanguage       = $defaultLanguage;
 	}
 
-	public function addHooks() {
-		if ( 0 === count( $this->activeLanguages ) ) {
+	abstract public function addHooks();
+
+	/**
+	 * @param array $args
+	 */
+	protected function setFullIndexArgs( $args ) {
+		$this->fullIndexArgs = $args;
+	}
+
+	protected function setUpAndRun() {
+		$this->prepare();
+		if ( empty( $this->status->get('currentLanguage') ) ) {
 			return;
 		}
+		$this->maybePutMapping();
+		$this->beforeFullIndex();
 
-		add_action( 'wp_ajax_ep_index', [ $this, 'action_wp_ajax_ep_index' ], 9 );
-		add_action( 'wp_ajax_ep_cancel_index', [ $this, 'action_wp_ajax_ep_cancel_index' ], 9 );
-	}
+		// This happens on an AJAX call, hence on admin: force the display-as-translated snippet in queries
+		add_filter( 'wpml_should_use_display_as_translated_snippet', '__return_true' );
 
-	private function setUp() {
-		$this->status->prepare();
+		$this->runFullIndex( $this->fullIndexArgs );
 	}
 
-	private function tearDown() {
+	protected function tearDown() {
 		$this->indicesManager->clearCurrentIndexLanguage();
 		$this->status->delete();
 	}
@@ -82,25 +95,14 @@ private function clearCurrentLanguage() {
 		$this->indicesManager->clearCurrentIndexLanguage();
 	}
 
-	private function isDashboardSync() {
-		if ( ! check_ajax_referer( 'ep_dashboard_nonce', 'nonce', false ) || ! EP_DASHBOARD_SYNC ) {
-			wp_send_json_error( null, 403 );
-			exit;
-		}
-
-		$index_meta = Utils\get_indexing_status();
-
-		if ( isset( $index_meta['method'] ) && 'cli' === $index_meta['method'] ) {
-			return false;
-		}
-
-		return true;
+	private function prepare() {
+		$this->status->prepare();
 	}
 
 	private function maybePutMapping() {
 		$putMapping = ! empty( $_REQUEST['put_mapping'] );
 
-		if ( $putMapping && false === $this->status->get('putMapping') ) {
+		if ( ( $putMapping || $forcePutMapping ) && false === $this->status->get('putMapping') ) {
 			$this->indicesManager->clearAllIndices();
 			$this->status->set('putMapping', true);
 		}
@@ -116,44 +118,31 @@ private function beforeFullIndex() {
 		$this->status->logIndexablesToReset( $this->deactivateIndexables() );
 	}
 
-	public function action_wp_ajax_ep_cancel_index() {
-		if ( false === $this->isDashboardSync() ) {
-			return;
-		}
-		$this->tearDown();
-	}
-
-	public function action_wp_ajax_ep_index() {
-		if ( false === $this->isDashboardSync() ) {
-			return;
-		}
-		$this->setUp();
-		if ( empty( $this->status->get('currentLanguage') ) ) {
-			return;
-		}
-		$this->maybePutMapping();
-		$this->beforeFullIndex();
-
-		// This happens on an AJAX call, hence on admin: force the display-as-translated snippet in queries
-		add_filter( 'wpml_should_use_display_as_translated_snippet', '__return_true' );
-
-		IndexHelper::factory()->full_index(
+	/**
+	 * @param array $forcedArgs
+	 */
+	private function runFullIndex( $forcedArgs = [] ) {
+		$args = array_merge(
 			[
 				'method'        => 'dashboard',
-				'put_mapping'   => false,
-				'output_method' => [ $this, 'indexOutput' ],
-				'show_errors'   => true,
 				'network_wide'  => 0,
-			]
+				'show_errors'   => true,
+			],
+			$forcedArgs
 		);
+
+    $args['put_mapping']   = false;
+    $args['output_method'] = [ $this, 'indexOutput' ];
+
+		IndexHelper::factory()->full_index( $args );
 	}
 
 	private function syncComplete() {
 		$message = [
-			'message' => 'Sync complete',
+			'message'    => 'Sync complete',
 			'index_meta' => null,
-			'totals' => $this->status->get('totals'),
-			'status' => 'success'
+			'totals'     => $this->status->get('totals'),
+			'status'     => 'success'
 		];
 		$this->tearDown();
 		wp_send_json_success( $message );
@@ -200,9 +189,9 @@ private function setLanguageCompletedResponse( $message ) {
 		// Hijack the message data so the next language gets processed
 		$message['totals']     = [];
 		$message['index_meta'] = [
-			'method' => 'web',
-			'totals' => $this->status->get('totals'),
-			'sync_stack' => [],
+			'method'      => 'web',
+			'totals'      => $this->status->get('totals'),
+			'sync_stack'  => [],
 			'put_mapping' => $this->status->get('putMapping'),
 		];
 		return $message;
diff --git a/src/Sync/DashboardAjax.php b/src/Sync/DashboardAjax.php
new file mode 100644
index 0000000..be10658
--- /dev/null
+++ b/src/Sync/DashboardAjax.php
@@ -0,0 +1,59 @@
+<?php
+
+namespace WPML\ElasticPress\Sync;
+
+use ElasticPress\Indexables;
+use ElasticPress\IndexHelper;
+use ElasticPress\Utils;
+
+use WPML\ElasticPress\Manager\Indices;
+use WPML\ElasticPress\Manager\DashboardStatus;
+
+use WPML\ElasticPress\Sync\Dashboard;
+
+use WPML\ElasticPress\Traits\ManageIndexables;
+
+/**
+ * Before ElasticPress 5.0.0 the Dashboard sync was run over AJAX.
+ */
+class DashboardAjax extends Dashboard {
+
+	public function addHooks() {
+		if ( 0 === count( $this->activeLanguages ) ) {
+			return;
+		}
+
+		add_action( 'wp_ajax_ep_index', [ $this, 'action_wp_ajax_ep_index' ], 9 );
+		add_action( 'wp_ajax_ep_cancel_index', [ $this, 'action_wp_ajax_ep_cancel_index' ], 9 );
+	}
+
+  private function isDashboardSync() {
+		if ( ! check_ajax_referer( 'ep_dashboard_nonce', 'nonce', false ) || ! EP_DASHBOARD_SYNC ) {
+			wp_send_json_error( null, 403 );
+			exit;
+		}
+
+		$index_meta = Utils\get_indexing_status();
+
+		if ( isset( $index_meta['method'] ) && 'cli' === $index_meta['method'] ) {
+			return false;
+		}
+
+		return true;
+	}
+
+  public function action_wp_ajax_ep_index() {
+		if ( false === $this->isDashboardSync() ) {
+			return;
+		}
+		$this->setUpAndRun();
+	}
+
+  public function action_wp_ajax_ep_cancel_index() {
+		if ( false === $this->isDashboardSync() ) {
+			return;
+		}
+		$this->tearDown();
+	}
+
+}
diff --git a/src/Sync/DashboardRest.php b/src/Sync/DashboardRest.php
new file mode 100644
index 0000000..73b5ab0
--- /dev/null
+++ b/src/Sync/DashboardRest.php
@@ -0,0 +1,69 @@
+<?php
+
+namespace WPML\ElasticPress\Sync;
+
+use ElasticPress\Indexables;
+use ElasticPress\IndexHelper;
+use ElasticPress\Utils;
+
+use WPML\ElasticPress\Manager\Indices;
+use WPML\ElasticPress\Manager\DashboardStatus;
+
+use WPML\ElasticPress\Sync\Dashboard;
+
+use WPML\ElasticPress\Traits\ManageIndexables;
+
+/**
+ * After ElasticPress 5.0.0 the Dashboard sync was run over the REST API.
+ */
+class DashboardRest extends Dashboard {
+
+	public function addHooks() {
+		if ( 0 === count( $this->activeLanguages ) ) {
+			return;
+		}
+
+		add_filter( 'rest_request_before_callbacks', [ $this, 'rest_request_before_callbacks' ], 10, 3 ) ;
+	}
+
+	private function isSyncMethod( $method, $request ) {
+		if ( $method !== $request->get_method() ) {
+			return false;
+		}
+
+		$route = $request->get_route();
+		if ( preg_match( "/^\/elasticpress\/v\d+\/sync$/", $route ) ) {
+			return true;
+		}
+	
+		return false;
+	}
+
+	/**
+	 * @param  \WP_REST_Response|\WP_HTTP_Response|\WP_Error|mixed $response
+	 * @param  array                                               $handler
+	 * @param  \WP_REST_Request                                    $request
+	 *
+	 * @return \WP_REST_Response|\WP_HTTP_Response|\WP_Error|mixed
+	 */
+	public function rest_request_before_callbacks( $response, $handler, $request  ) {
+		$capability = Utils\get_capability();
+
+		if ( ! current_user_can( $capability ) ) {
+			return $response;
+		}
+		
+		if ( $this->isSyncMethod( 'POST', $request ) ) {
+			$this->setFullIndexArgs( $request->get_params() );
+			$this->setUpAndRun();
+		}
+
+		if ( $this->isSyncMethod( 'DELETE', $request ) ) {
+			$this->tearDown();
+		}
+
+		return $response;
+
+	}
+
+}
\ No newline at end of file
diff --git a/src/Sync/Singular.php b/src/Sync/Singular.php
index 81fba41..066cc06 100644
--- a/src/Sync/Singular.php
+++ b/src/Sync/Singular.php
@@ -13,6 +13,18 @@ class Singular {
 
 	use CrudPropagation;
 
+	/**
+	 * In ElasticPress 5.0.0, the \ElasticPress\SyncManager::sync_queue attribute mutated:
+	 * - Before, it was an array indexed by post IDs with a TRUE value for those modified.
+	 * - After, those same entries got spread in parent arrays per site ID.
+	 *
+	 * For example, [ 123 => true ] became [ 1 => [ 123 => true ] ],
+	 * where 1 is the a block ID and 123 is a post ID for a post in the blog with ID equal 1.
+	 *
+	 * Nice for them to change some public data structure, right? Well, life!
+	 */
+	const SYNC_QUEUE_API_CHANGE_V1 = '5.0.0';
+
 	/** @var Indexables */
 	private $indexables;
 
@@ -25,22 +37,28 @@ class Singular {
 	/** @var string */
 	private $defaultLanguage;
 
+	/** @var string */
+	private $elasticPressVersion;
+
 	/**
 	 * @param Indexables $indexables
 	 * @param Indices    $indicesManager
 	 * @param array      $activeLanguages
 	 * @param string     $defaultLanguage
+	 * @param string     $elasticPressVersion
 	 */
 	public function __construct(
 		Indexables $indexables,
 		Indices    $indicesManager,
 		$activeLanguages,
-		$defaultLanguage
+		$defaultLanguage,
+		$elasticPressVersion
 	) {
-		$this->indexables      = $indexables;
-		$this->indicesManager  = $indicesManager;
-		$this->activeLanguages = $activeLanguages;
-		$this->defaultLanguage = $defaultLanguage;
+		$this->indexables          = $indexables;
+		$this->indicesManager      = $indicesManager;
+		$this->activeLanguages     = $activeLanguages;
+		$this->defaultLanguage     = $defaultLanguage;
+		$this->elasticPressVersion = $elasticPressVersion;
 	}
 
 	public function addHooks() {
@@ -63,6 +81,22 @@ function( $hook ) {
 		);
 	}
 
+	/**
+	 * @param  \ElasticPress\SyncManager $syncManager
+	 *
+	 * @return int[]
+	 */
+	private function getIdsInSyncQueue( $syncManager ) {
+		$syncQueue = $syncManager->sync_queue;
+
+		if ( version_compare( $this->elasticPressVersion, self::SYNC_QUEUE_API_CHANGE_V1, '<' ) ) {
+			return array_keys( $syncQueue );
+		}
+		$currentBlogId           = get_current_blog_id();
+		$syncQueueForCurrentBlog = $syncQueue[ $currentBlogId ] ?? [];
+		return array_keys( $syncQueueForCurrentBlog ) ;
+	}
+
 	/**
 	 * @param  bool                      $halt
 	 * @param  \ElasticPress\SyncManager $syncManager
@@ -94,7 +128,7 @@ public function manageSyncQueue( $halt, $syncManager, $indexableSlug ) {
 		//     - Maybe remove the ID for the default language post from the current language index
 		//         - Skip those which do not exist in the current language index (when updating an existing translation, for example)
 		//     - Maybe sync the default language post in the default language index to sync language field values
-		$this->propagateIds( array_keys( $syncManager->sync_queue ) );
+		$this->propagateIds( $this->getIdsInSyncQueue( $syncManager ) );
 
 		$this->manageIds( 'sync', 'main' );
 		$this->manageIds( 'delete', 'related' );