It gets turned off on upgrade. You have to turn it back on.
It turned off during my upgrade. How do you turn it back on? I tried changing it to something else, saving it, and then changing it back to dashboard, but it still does not work for me using F12 or a hot corner. Thank you for your help.
Use the Launcher application, or rocket ship icon, to select the Dashboard whose icon is a round black gauge face with five app icons.
Start Dashboard explicitly once from here, and then it should correctly kick-in when you access your Hot Corner set to Dashboard.