diff --git a/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php b/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
index 1b32458..e1eb459 100644
--- a/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
@@ -169,6 +169,18 @@ public function __destruct() {
   }
 
   /**
+   * Gets all the attached databases.
+   *
+   * @return array
+   *   An array of attached database names.
+   *
+   * @see \Drupal\Core\Database\Driver\sqlite\Connection::__construct()
+   */
+  public function getAttachedDatabases() {
+    return $this->attachedDatabases;
+  }
+
+  /**
    * SQLite compatibility implementation for the IF() SQL function.
    */
   public static function sqlFunctionIf($condition, $expr1, $expr2 = NULL) {
diff --git a/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php b/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
index 7f7ff2d..9130620 100644
--- a/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
@@ -696,17 +696,27 @@ public function fieldSetNoDefault($table, $field) {
     $this->alterTable($table, $old_schema, $new_schema);
   }
 
+  /**
+   * {@inheritdoc}
+   */
   public function findTables($table_expression) {
-    $info = $this->getPrefixInfo($table_expression);
-
-    // Can't use query placeholders for the schema because the query would have
-    // to be :prefixsqlite_master, which does not work. We also need to ignore
-    // the internal SQLite tables.
-    $result = db_query("SELECT name FROM " . $info['schema'] . ".sqlite_master WHERE type = :type AND name LIKE :table_name AND name NOT LIKE :pattern", array(
-      ':type' => 'table',
-      ':table_name' => $table_expression,
-      ':pattern' => 'sqlite_%',
-    ));
-    return $result->fetchAllKeyed(0, 0);
+    $tables = [];
+
+    // Try to find tables in all attached databases.
+    $attached_dbs = $this->connection->getAttachedDatabases();
+    foreach ($attached_dbs as $schema) {
+      // Can't use query placeholders for the schema because the query would have
+      // to be :prefixsqlite_master, which does not work. We also need to ignore
+      // the internal SQLite tables.
+      $result = db_query("SELECT name FROM " . $schema . ".sqlite_master WHERE type = :type AND name LIKE :table_name AND name NOT LIKE :pattern", array(
+        ':type' => 'table',
+        ':table_name' => $table_expression,
+        ':pattern' => 'sqlite_%',
+      ));
+      $tables += $result->fetchAllKeyed(0, 0);
+    }
+
+    return $tables;
   }
+
 }
diff --git a/core/modules/system/src/Tests/Database/SchemaTest.php b/core/modules/system/src/Tests/Database/SchemaTest.php
index 4511320..fb5a1c2 100644
--- a/core/modules/system/src/Tests/Database/SchemaTest.php
+++ b/core/modules/system/src/Tests/Database/SchemaTest.php
@@ -733,7 +733,6 @@ public function testFindTables() {
     // Check the "all tables" syntax.
     $tables = Database::getConnection()->schema()->findTables('%');
     sort($tables);
-    debug($tables);
     $expected = [
       // The 'config' table is added by
       // \Drupal\simpletest\KernelTestBase::containerBuild().