diff --git a/core/modules/migrate_drupal/migrate_drupal.module b/core/modules/migrate_drupal/migrate_drupal.module
index d31feed..49b5be9 100644
--- a/core/modules/migrate_drupal/migrate_drupal.module
+++ b/core/modules/migrate_drupal/migrate_drupal.module
@@ -5,11 +5,13 @@
  * Provides migration from other Drupal sites.
  */
 
+use Drupal\Core\Database\DatabaseExceptionWrapper;
 use Drupal\Core\Routing\RouteMatchInterface;
 use Drupal\migrate\Exception\RequirementsException;
 use Drupal\migrate\MigrateExecutable;
 use Drupal\migrate\MigrateMessage;
 use Drupal\migrate\Plugin\Migration;
+use Drupal\migrate\Plugin\RequirementsInterface;
 
 /**
  * Implements hook_help().
@@ -44,10 +46,13 @@ function migrate_drupal_migration_plugins_alter(&$definitions) {
     $vocabulary_migration = new Migration([], uniqid(), $vocabulary_migration_definition);
 
     try {
-      $vocabulary_migration->checkRequirements();
+      $source_plugin = $vocabulary_migration->getSourcePlugin();
+      if ($source_plugin instanceof RequirementsInterface) {
+        $source_plugin->checkRequirements();
+      }
       $executable = new MigrateExecutable($vocabulary_migration, new MigrateMessage());
       $process = ['vid' => $definitions['d6_taxonomy_vocabulary']['process']['vid']];
-      foreach ($vocabulary_migration->getSourcePlugin() as $row) {
+      foreach ($source_plugin as $row) {
         $executable->processRow($row, $process);
         $source_vid = $row->getSourceProperty('vid');
         $plugin_ids = ['d6_term_node:' . $source_vid, 'd6_term_node_revision:' . $source_vid];
@@ -63,6 +68,10 @@ function migrate_drupal_migration_plugins_alter(&$definitions) {
       // if you have a Drupal 7 source site then the requirements will not be
       // met for the d6_taxonomy_vocabulary migration.
     }
+    catch (DatabaseExceptionWrapper $e) {
+      // When the definitions are loaded it is possible the tables will not
+      // exist.
+    }
 
   }
 }