I just did a ComfortUpdate to 2.50 build 160725. After update my survey would not run (blank white screen in browser). Whewn editing the survey all questions were present. However, dropdown questions would not display options.

Anyone else have problems?
Paul Earley

This turned out to be a template problem. Using the default template fixed the problem.

I have the same problem. How do I change the template to default? There is no access, just white screen.

Sorry, I have a different problem. After providing my user id and password on the admin login, I see a white screen, instead of admin panel.
I was using a custom template and if there is a way to reset it to default, it may help.

you may try to clear your browser cache...