Set up a web service ( https://docs.moodle.org/35/en/Using_web_services#Creating_a_service ) with core_course_updated_courses and a token for the admin user. Make sure your php config has the post_max_size and upload_max_filesize both set to 8M Set "Maximum uploaded file size" (maxbytes) to 2MB for the Moodle install via admin Now, create a new course and save. Check the "Files and uploads" settings for the course and verify it's set to "site upload limit (2M)" Try to upload a 3M file to the course home (drag and drop) and verify it fails. Normal, as we've got a 2M limit right now. Now, run the webservice call: curl 'http://localhost/master/webservice/rest/server.php?moodlewsrestformat=json' --data 'wsfunction=core_course_update_courses&wstoken=TOKEN&courses[0][id]=COURSEID&courses[0][maxbytes]=0' | python -m "json.tool" swapping in your token and courseid as needed. Check the course settings and notice that maxbytes is now set to the site limit as before. Check the mdl_course table and notice that maxbytes has been set to 0 Now, change the "Maximum uploaded file size" (maxbytes) to 5MB for the Moodle install via admin again. Check the course settings again, and notice the maxbytes is still set to "Site limit (5M)". Upload the 3M file again, and verify the upload is successful. Now, run the web service call again, this time setting maxbytes to 99999999  Check the course settings and verify the max upload size is listed as 5MB (i.e. it has been capped at the site limit).