diff --git a/core/modules/migrate/src/Plugin/migrate/process/Callback.php b/core/modules/migrate/src/Plugin/migrate/process/Callback.php
index a7f09312ec..c08b297fb9 100644
--- a/core/modules/migrate/src/Plugin/migrate/process/Callback.php
+++ b/core/modules/migrate/src/Plugin/migrate/process/Callback.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\migrate\Plugin\migrate\process;
 
+use Drupal\migrate\MigrateException;
 use Drupal\migrate\MigrateExecutableInterface;
 use Drupal\migrate\ProcessPluginBase;
 use Drupal\migrate\Row;
@@ -44,7 +45,7 @@
  *
  * @code
  * source:
- *   plugin: ...
+ *   plugin: foo
  *   constants:
  *     slash: /
  * process:
@@ -86,7 +87,7 @@ public function __construct(array $configuration, $plugin_id, $plugin_definition
   public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
     if (!empty($this->configuration['unpack_source'])) {
       if (!is_array($value)) {
-        throw new \InvalidArgumentException('When "unpack_source" is set, the source must be an array.');
+        throw new MigrateException(sprintf("When 'unpack_source' is set, the source must be an array., instead it was of type '%s'", gettype($value)));
       }
       return call_user_func($this->configuration['callable'], ...$value);
     }