diff --git a/core/modules/node/src/Plugin/migrate/D6NodeDeriver.php b/core/modules/node/src/Plugin/migrate/D6NodeDeriver.php
index 3fba70a..c24047b 100644
--- a/core/modules/node/src/Plugin/migrate/D6NodeDeriver.php
+++ b/core/modules/node/src/Plugin/migrate/D6NodeDeriver.php
@@ -4,6 +4,7 @@
 
 use Drupal\Component\Plugin\Derivative\DeriverBase;
 use Drupal\Component\Plugin\Exception\PluginNotFoundException;
+use Drupal\Core\Database\ConnectionNotDefinedException;
 use Drupal\Core\Database\DatabaseExceptionWrapper;
 use Drupal\Core\Plugin\Discovery\ContainerDeriverInterface;
 use Drupal\migrate\Exception\RequirementsException;
@@ -151,6 +152,10 @@ public function getDerivativeDefinitions($base_plugin_definition) {
       // MigrationPluginManager gathers up the migration definitions but we do
       // not actually have a Drupal 6 source database.
     }
+    catch (ConnectionNotDefinedException $e) {
+      // It's also possible that the source database is not defined. This can
+      // happen if a source migration is unused or only used as a base.
+    }
 
     return $this->derivatives;
   }
diff --git a/core/modules/node/src/Plugin/migrate/D7NodeDeriver.php b/core/modules/node/src/Plugin/migrate/D7NodeDeriver.php
index bd3d8b9..05b47ec 100644
--- a/core/modules/node/src/Plugin/migrate/D7NodeDeriver.php
+++ b/core/modules/node/src/Plugin/migrate/D7NodeDeriver.php
@@ -4,6 +4,7 @@
 
 use Drupal\Component\Plugin\Derivative\DeriverBase;
 use Drupal\Component\Plugin\Exception\PluginNotFoundException;
+use Drupal\Core\Database\ConnectionNotDefinedException;
 use Drupal\Core\Database\DatabaseExceptionWrapper;
 use Drupal\Core\Plugin\Discovery\ContainerDeriverInterface;
 use Drupal\migrate\Exception\RequirementsException;
@@ -121,6 +122,10 @@ public function getDerivativeDefinitions($base_plugin_definition) {
       // MigrationPluginManager gathers up the migration definitions but we do
       // not actually have a Drupal 7 source database.
     }
+    catch (ConnectionNotDefinedException $e) {
+      // It's also possible that the source database is not defined. This can
+      // happen if a source migration is unused or only used as a base.
+    }
 
     return $this->derivatives;
   }