Android Studio Rendering Problems : The following classes could not be found

Question

I just update Android Studio, and when I restarted it, the preview window rendering failed, and I was told that

The following classes could not be fo

Answer 1

I faced this error when I created second activity in my project in the newly updated Android Studio,I solved it simply by copy pasting the whole xml code from first layout to the second and then I just removed the code that's unnecessary.