diff --git a/lib/Doctrine/DBAL/Schema/Synchronizer/AbstractSchemaSynchronizer.php b/lib/Doctrine/DBAL/Schema/Synchronizer/AbstractSchemaSynchronizer.php
index 7cfd1f2c00f..85f4ae6d3d0 100644
--- a/lib/Doctrine/DBAL/Schema/Synchronizer/AbstractSchemaSynchronizer.php
+++ b/lib/Doctrine/DBAL/Schema/Synchronizer/AbstractSchemaSynchronizer.php
@@ -3,6 +3,7 @@
 namespace Doctrine\DBAL\Schema\Synchronizer;
 
 use Doctrine\DBAL\Connection;
+use Doctrine\Deprecations\Deprecation;
 use Throwable;
 
 /**
@@ -18,6 +19,12 @@ abstract class AbstractSchemaSynchronizer implements SchemaSynchronizer
     public function __construct(Connection $conn)
     {
         $this->conn = $conn;
+
+        Deprecation::trigger(
+            'doctrine/dbal',
+            'https://github.com/doctrine/dbal/pull/4213',
+            'SchemaSynchronizer API is deprecated without a replacement and will be removed in DBAL 3.0'
+        );
     }
 
     /**