Version 4.7.6

applications/nexus/sources/Gateway/Gateway.php

@@ -210,7 +210,10 @@ class _Gateway extends \IPS\Node\Model
 			$values['countries'] = \is_array( $values['paymethod_countries'] ) ? implode( ',', $values['paymethod_countries'] ) : $values['paymethod_countries'];
 		}
 
-		$values['validationfile'] = (string) $values['m_validationfile'];
+		if( isset( $values['m_validationfile'] ) )
+		{
+			$values['validationfile'] = (string) $values['m_validationfile'];
+		}
 
 		$settings = array();
 		foreach ( $values as $k => $v )