A form for editing defect is probably misconfigured. It happens, that if I return to this form, it is empty. All texts, that I wrote, is lost.

Use case:
1) open bug
2) spend 30 minutes by writing description
3) submit form => error 2800, expired authentication token
4) press browser Back button => description is empty => heart attack, another dead mantis user

Yesterday I had different use case with the same result. I used touchpad instead of mouse and pressed something else than submit. Again my data was lost, when I returned and I had to write it again.

This behaviour is very rare. The most web applications do not reset their form on back button. Please let the content survive.

Second issue is that error 2800 shall appear on top of the form with prefilled values, so I can just press Submit again.