Idea Summary
When you want to apply some custom CSS using the Theme Roller editor and the code contains a mistake, it will raise the error “Could not update theme style”.
Now Theme Roller got stuck and you need to login again in Application Builder.

Use Case
In our case our custom CSS part is almost 30K big. That could be an issue as well, maybe?

Preferred Solution
1. The connection link between the application builder and the runtime application should not be lost.
2. Better explain why the theme style could not be saved