I am currently testing backup/restore of my courses from Moodle 1.5 (on a distant site) to Moodle 1.6 (on my local install). In my 1.5 courses I have a number of questions of the Cloze type. Because the handling of quizzes and questions has beeen changed in 1.6, and because the Cloze-type questions are special, there is a special test in \question\type\multianswer\questiontype.php which yields error messages. Unfortunately, when these error messages are generated during the restoration of a course, the restoration STOPS! This is a serious problem, and I suggest replacing the error report with a notify report, which will still display the error messages but will allow the restore process to continue. I prefer this, because, once the restore process is over, I can alway edit the multianswer questions one by one and make them work.
around line 535
error(The cloze question $state->question is missing its options);
error(Can't find the subquestion $wrappedquestionid that is used as part $seqnum in cloze question $state->question);
notify(The cloze question $state->question is missing its options);
notify(Can't find the subquestion $wrappedquestionid that is used as part $seqnum in cloze question $state->question);