"This block has encountered an error and cannot be previewed"

Hi Knuth,

What specific Block is that?

Headline

Did you make any changes to the Headline Blocks through the code editor?

Did you also make any recent changes in your site recently before the issue occurred?

Have you also tried #1 here?: https://docs.generatepress.com/article/debugging-tips/

It would be good to take a backup of your site before doing so.