Hello
I'm having a very similar problem.
Site administration > Plugins > Activity modules > Assignment > Feedback plugins > Annotate PDF:
Annotate PDF
Can not read file, either file does not exist or there are permission problems
More information about this error
Debug info: [dataroot]/filedir/d6/13/d613d55f37bb76d38d4ffb4b7b83e6c694778c30
Error code: storedfilecannotread
Stack trace:
line 187 of /lib/filestorage/stored_file.php: file_exception thrown
line 881 of /lib/filestorage/stored_file.php: call to stored_file->update()
line 424 of /lib/filelib.php: call to stored_file->set_source()
line 8330 of /lib/adminlib.php: call to file_prepare_draft_area()
line 1376 of /lib/adminlib.php: call to admin_setting_configstoredfile->output_html()
line 125 of /admin/settings.php: call to admin_settingpage->output_html()
Everything seems to work fine when using the tool to annotate a submitted PDF but the following error appears after clicking Save changes:
Can not read file, either file does not exist or there are permission problems
More information about this error
Debug info: [dataroot]/filedir/d6/13/d613d55f37bb76d38d4ffb4b7b83e6c694778c30
Error code: storedfilecannotread
Stack trace:
line 485 of /lib/filestorage/stored_file.php: file_exception thrown
line 567 of /mod/assign/feedback/editpdf/classes/document_services.php: call to stored_file->copy_content_to()
line 205 of /mod/assign/feedback/editpdf/locallib.php: call to assignfeedback_editpdf\document_services::generate_feedback_document()
line 6303 of /mod/assign/locallib.php: call to assign_feedback_editpdf->save()
line 6471 of /mod/assign/locallib.php: call to assign->apply_grade_to_user()
line 6528 of /mod/assign/locallib.php: call to assign->save_grade()
line 453 of /mod/assign/locallib.php: call to assign->process_save_grade()
line 53 of /mod/assign/view.php: call to assign->view()
I can reopen the annotated PDF and my feedback annotations are still there but the student's view does not show the annotations.
Feedback comments added to the text box in the grading window are saved and visible to both teacher and student but the grade is not saved.
I have also found similar records in the mdl_files table. They all refer to the cross.png image.
I'm also aware of this: https://tracker.moodle.org/browse/MDLSITE-2622 thread elsewhere.
Any advice appreciated.