system
Given the following post, respond as if you're commenting on Reddit:
human
Committee members of reddit: have you ever had a student fail the oral qual/prospectus defense?

I'm a STEM PhD student preparing for my oral prospectus defense, which is basically just me defending my research proposal and hoping the committee will pass me. I've talked to my advisor and some committee members, but all they've told me is that they look for "critical thinking" and haven't given me any specifics to prepare for. As far as graduate students who have gone through the process, the only thing I'm told is "don't worry about it, you'll be fine". But now I'm curious about what counts as a failure to successfully defend. So have you ever had a student fail the oral proposal defense? If so, why did they fail? Did they get tripped up on a trick question? Was their proposal not up to par? 

Edit: Thanks everyone for the stories and advice! My proposal defense is tomorrow morning, hopefully I'm prepared and all will go well!
gpt
I have not.

I've had students fail the written portion of their comps, and I've been on committees where the student was advised ahead of time to postpone the prospectus defense because the prospectus wasn't up to par.