Environment: Ghostscript. If it's not installed, you can execute the following commands from the console: $ apt-get update $ apt-get install ghostscript Testing instructions: Login as admin. Access to "Site administration / Server / System paths", set "Path to ghostscript" to '/usr/bin/gs' or the corresponding to your environment and Save changes. Check a green check is displayed near the "Path to ghostscript" field. Access to "Site administration / Plugins / Activity modules / Assignment / Feedback plugins / Annotate PDF" and check "Annotate PDF" feedback plugin is enabled. Create a student. Create a course. Create an assignment with Annotate PDF feedback ticked. Enrol the student into the course. Login as the student. Submit the attached file (excerpts.pdf) to the assignment. Hack the code and add lines between these two brackets https://github.com/golenkovm/moodle/blob/master-MDL-66626/mod/assign/feedback/editpdf/classes/document_services.php#L466-L467  : if ($i == 5 ) { mtrace( "Please, terminate me now!" ); sleep( 10 ); } Open terminal and run scheduled task: php admin/tool/task/cli/schedule_task.php --execute= '\assignfeedback_editpdf\task\convert_submissions' Wait for "Please, terminate me now." message and terminate the script (Ctrl+C or close the terminal). root @c69335460f7f :/siteroot# php admin/tool/task/cli/schedule_task.php --execute= '\assignfeedback_editpdf\task\convert_submissions' Execute scheduled task: Prepare submissions for annotation (assignfeedback_editpdf\task\convert_submissions) Convert 1 submission attempt(s) for assignment 1 Please, terminate me now! ^C root @c69335460f7f :/siteroot# Run SQL: select filearea, itemid, filepath, filename, filesize from mdl_files where filearea = 'pages' order by timecreated desc; Confirm , the number of pages is less than 16 (the total number of pages in submitted pdf): filearea | itemid | filepath | filename | filesize ----------+--------+----------+-----------------+---------- pages | 1 | / | image_page0.png | 34823 pages | 1 | / | . | 0 pages | 1 | / | image_page1.png | 47312 pages | 1 | / | image_page2.png | 78120 pages | 1 | / | image_page3.png | 76542 pages | 1 | / | image_page4.png | 57169 pages | 1 | / | image_page5.png | 122690 ( 7 rows) Remove the hack added in 11. Login as a teacher (admin) and grade submission. Confirm , that PDF Annotate viewer displays the same number of pages as the original document has (16). Run SQL: select filearea, itemid, filepath, filename, filesize from mdl_files where filearea = 'pages' order by timecreated desc; Confirm , that pages have been re-generated (there are 16 pages with newer timecreated): filearea | itemid | filepath | filename | filesize ----------+--------+----------+------------------+---------- pages | 1 | / | image_page0.png | 34823 pages | 1 | / | . | 0 pages | 1 | / | image_page1.png | 47312 pages | 1 | / | image_page2.png | 78120 pages | 1 | / | image_page3.png | 76542 pages | 1 | / | image_page4.png | 57169 pages | 1 | / | image_page5.png | 122690 pages | 1 | / | image_page6.png | 83458 pages | 1 | / | image_page7.png | 80188 pages | 1 | / | image_page8.png | 160127 pages | 1 | / | image_page9.png | 65057 pages | 1 | / | image_page10.png | 74191 pages | 1 | / | image_page11.png | 68087 pages | 1 | / | image_page12.png | 66612 pages | 1 | / | image_page13.png | 72495 pages | 1 | / | image_page14.png | 70981 pages | 1 | / | image_page15.png | 55567 ( 17 rows)