Posts not displayed after update 4.9.8

WordPress 4.9.8 / Theme Hestia Child.

I really need help, I updated to the latest version of WP and Hestia and now none my posts can be displayed anymore!!! for example : https://kaiserhaus-baden.at/spezialfuehrung-eine-stadt-im-banne-des-militaers-mit-dr-christine-triebnig-loeffler-zur-ausstellung/

I can edit them in the backend – they are not deleated but when I want to see in the frontend them there is just a blank page, not even an error message..

Please help..

Thank you!

The page I need help with: [log in to see the link]