Version: 3.0.4 update jobs gives white screen

I use backWPup for years on several sites and it worked great. Today I updated to version 3.0.4. and it seems to be broken. When I tried to update the jobs (general, schedule, files plugins and so on) and pressed the blue update button I get a white screen and see in the browserbar

https://www.mysite.com/wp-admin/admin-post.php?action=backwpup

I only can use the browser back button to leave this screen. I removed backWPup from my site and downloaded it again from www.ads-software.com but had the same problem.
Is this a resolvabel problem or do I lose my favorite backup plugin?

https://www.ads-software.com/extend/plugins/backwpup/