To test, you need access to the PHP error log (ensure that new error logs are added e.g. add an \Exception in config.php so something like that) Through WS (via curl) Create a course with an assignment activity. Enroll a student. As an admin, enable "Mobile services": Plugins ► Web Services ► Mobile Create a Token for the student: Click on Site administration ► Plugins ► Web services ► Manage tokens Next, you can do a CURL REST: You need to replace the WSTOKEN, ASSIGN_INSTANCE_ID and the URL of your Moodle instance (MOODLE_INSTANCE). curl 'http://MOODLE_INSTANCE/webservice/rest/server.php?moodlewsrestformat=json' --data 'assignid=ASSIGN_INSTANCE_ID&wsfunction=mod_assign_get_submission_status&wstoken=WSTOKEN' | python -m "json.tool" Ensure you don't see in error_log a message like: Got error 'PHP message: Debugging: This page did not call $PAGE->set_url(...). Using http://moodlehq.local/webservice/rest/server.php?moodlewsrestformat=json in * line 600 of /lib/pagelib.php: call to debugging() * line 820 of /lib/pagelib.php: call to moodle_page->magic_get_url() * line 249 of /mod/assign/locallib.php: call to moodle_page->__get() * line 5011 of /mod/assign/locallib.php: call to assign->get_return_action() * line 2348 of /mod/assign/externallib.php: call to assign->get_assign_submission_status_renderable() * line 1397 of /webservice/lib.php: call to mod_assign_external::get_submission_status() * line 1261 of /webservice/lib.php: call to webservice_base_server->execute() * line 44 of /webservice/rest/server.php: call to webservice_base_server->run()