How to reproduce: Create a course with a student user. Create a book with at least 1 chapter (without images, just text). Please write down the cmid and the sectionid of the book, you will need it later. Log in as an admin Enable "Mobile services": Site administration ► Mobile app ► Mobile settings Create a Token for the student user. Click on Site administration ► Plugins ► Web services ► Manage tokens Next, you can do a CURL REST call simulating a WS client with the student user . You need to replace the wstoken, courseid, cmid, sectionid and the URL of your moodle instance. curl 'http://localhost/m/stable_master/webservice/rest/server.php?moodlewsrestformat=json' --data 'courseid=9&options%5B0%5D%5Bname%5D=cmid&options%5B0%5D%5Bvalue%5D=355&options%5B1%5D%5Bname%5D=sectionid&options%5B1%5D%5Bvalue%5D=82&wsfunction=core_course_get_contents&wstoken=413ebb77feed0fde2e612290645df640' --compressed Please write down the " timemodified " returned by the book's chapter (inside the " contents " property). Edit the book's chapter and modify the chapter's content. Save the changes. Perform the REST call again and check that the timemodified has been updated with the timestamp when the chapter was updated.