External function core_calendar_external::submit_create_update_form does not work via the WS server

As admin, enable "Mobile services": Site administration ► Mobile app ► Mobile settings Create a Token in the mobile app service for the site admin Click on Site administration ► Plugins ► Web services ► Manage tokens In a browser, open the following URL but using your Moodle site and replacing the wstoken value with your site admin token value: http://localhost/m/stable_master/webservice/rest/server.php?moodlewsrestformat=json&wsfunction=core_calendar_submit_create_update_form&formdata=name%3DAPP%26eventtype%3Duser%26_qf__core_calendar_local_event_forms_create%3D1%26timestart%3D1561031947%26description[format]%3D1%26duration%3D0%26repeat%3D0%26id%3D0%26userid%3D2%26visible%3D1%26instance%3D0&moodlewssettingfilter=true&moodlewssettingfileurl=true&wstoken=e8a8eb4410ad85d6f76ffc7a908fb65a Check that you don't see any error in the page returned by the url Log-in into your Moodle site and go to the calendar and check that there is a event with name "APP" for the 20th of June