I have Ubuntu 18.4 and after the most recent update to version 1.8.7 all my notes and configuration have disappeared. How can I solve the problem?
First close Zettlr. Then you need to remove the ~/.config/Zettlr directory (with a capital Z), rename the ~/.config/zettlr directory (with a lowercase z) to ~/.config/Zettlr with an uppercase Z. Then start Zettlr 1.8.7 and it'll work again.