diff --git a/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php b/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
index 99537dd356..cd5cadb5b3 100644
--- a/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
@@ -461,6 +461,9 @@ public static function open(array &$connection_options = []) {
     }
     $connection_options['init_commands'] += [
       'sql_mode' => "SET sql_mode = '$sql_mode'",
+      // Set a low transaction level because otherwise busy Drupal sites run
+      // into transaction deadlocks.
+      'isolation' => "SET SESSION tx_isolation='READ-COMMITTED'",
     ];
 
     // Execute initial commands.