An error occurred during my exam/the exam froze/an error message appeared

All of the exam attempts have a resume feature built into them regardless if they are timed or not timed exams.  If an error occurs during your exam session, close the LockDown Browser and relaunch it.  When you relaunch the LockDown Browser, you will arrive where you left off, still be able to change your answer choices, flag questions, etc.  In a timed exam, the timer will continue to run and the exam will automatically complete when time is expired.  In an untimed exam, the exam will remain In Progress until you click the button in the exam to submit all of the questions to complete the exam.