Element 'params', attribute 'name': The attribute 'name' is not allowed. is thrown when a correct params xml should be accepted

If you want to edit a params object via the XML button then you get the error

Element 'params', attribute 'name': The attribute 'name' is not allowed.

after you click to the Accept button although the params element does not have an attribute.

WORKAROUND:
Disable the validation against the schema. For this edit the ./web/custom/custom.inc.php:

 
if(!defined('APP_SCHEDULER_SCHEMA_ENABLED'))  { define ( 'APP_SCHEDULER_SCHEMA_ENABLED', false ); }