New site installation In a terminal, tail your web server logs, e.g. # For an Ubuntu server: $ tail -f /var/log/apache2/error.log Start web installation Confirm you don't see the following in web server logs: [Tue Apr 05 23:48:47.286586 2022] [php7:notice] [pid 26] [client 172.23.0.1:55844] Default exception handler: Table "external_functions" does not exist Debug: \nError code: ddltablenotexist\n* line 665 of /lib/dml/moodle_database.php: dml_exception thrown\n* line 1621 of /lib/dml/moodle_database.php: call to moodle_database->where_clause()\n* line 73 of /lib/externallib.php: call to moodle_database->get_record()\n* line 196 of /lib/externallib.php: call to external_api::external_function_info()\n* line 81 of /lib/ajax/service.php: call to external_api::call_external_function()\n* line 33 of /lib/ajax/service-nologin.php: call to require_once()\n, referer: http://localhost:8000/admin/index.php Complete the installation Atto Image: Start writing a new forum discussion and add something to all required form fields. Drag-and-drop a large image into atto (it probably helps to use your browser developer tools to throttle your connection.) Verify that the "Submit" button of the form is disabled. Now, wait for the file upload to complete. You should see the loading icon in the atto area will disappear. Verify  that the "Submit" button of the form is enabled. Click the "Submit" button and Verify you are not prompted and that the form submits without error. File manager: Create an assignment in a course allowing file submissions. Log in as a student in the course, go to the assignment page. Open your browser's dev tools and in the network tab (chrome and firefox have this), you'll see a 'throttling' menu item near the right side. Set this to '3G' or the like, preferable as slow as you can set it. Now, drag a 1MB image file (or thereabouts in size) from your local filesystem to the submission area. Don't use the file selector dialogue. Verify that the "Submit" button of the form is disabled. Now, wait for the file upload to complete. You should see the file icon in the submission area and the grey bar will disappear. Verify  that the "Submit" button of the form is enabled. Click the "Submit" button and Verify you are not prompted and that the form submits without error. Site upgrade (from 3.9) Uninstall your site (e.g. if using MDK, " mdk uninstall -y ") In a terminal, tail your web server logs Install a 3.9 site $ git checkout MOODLE_39_STABLE Install the site. e.g. if using MDK $ mdk install Switch to the branch you're testing: 311 git checkout MOODLE_311_STABLE 400 git checkout MOODLE_400_STABLE master git checkout master Login as admin and run through the upgrade Confirm you don't see the following in web server logs: [Tue Apr 05 23:41:38.168464 2022] [php7:notice] [pid 19] [client 172.22.0.1:58420] Default exception handler: Can't find data record in database table external_functions. Debug: SELECT * FROM {external_functions} WHERE name = ?\n[array (\n 0 => 'media_videojs_get_language',\n)]\nError code: invalidrecord\n* line 1646 of /lib/dml/moodle_database.php: dml_missing_record_exception thrown\n* line 1622 of /lib/dml/moodle_database.php: call to moodle_database->get_record_select()\n* line 73 of /lib/externallib.php: call to moodle_database->get_record()\n* line 196 of /lib/externallib.php: call to external_api::external_function_info()\n* line 81 of /lib/ajax/service.php: call to external_api::call_external_function()\n, referer: http://localhost:8000/admin/index.php