In assignment settings enable allowsubmissionfromdate and duedate. Try to grant extension to a user with extension date earlier than allowsubmissionfromdate or duedate 1) Go to assignment page as a teacher 2) Go to assignment setting (Assignment administration->Edit settings) 3) In Availability section enable 'Allow submission from' and 'Due date'. Click 'Save and display' 4) Click 'View all submissions' button - after that you should see a list of users 5) For any user click Edit->Grant extension 5a) Confirm that you see the user name and avatar as part of the form 6) Enable Extension due date. Make sure it is earlier than 'Allow submission from' or 'Due date'. Click 'Save changes' 7) You should see a validation error and NOT an SQL exception error page. 8) Disable all submission plugin for that assignment 9) View all submissions and select a few of them, then select "Grant extension" in the bulk actions select box 9a) Confirm that you see up to 5 user names and avatars as part of the form 10) Enable Extension due date. Make sure it is earlier than 'Allow submission from' or 'Due date'. Click 'Save changes' 11) You should see a validation error and NOT an SQL exception error page.