I received this message after assigning menu items in the template manager. After resetting to "none" the error message went away. This did not affect my mobile menu settings either. My question is: Why do you have the option of assigning a menu in the template manager if it has no effect on the menu assigned and simply creates an error message?

1. There is no way to disable assigning a menu in template manager.
2. Did you read FAQ?
3. MJ displays warnings in such a cases (in the right column of MJ settings page).

Yes, I read the FAQ and assumed that the newly created menu module ("Mobile-menu") must have been at the root of the problem. I went to the Template Manager and under "Menu Assignment" > "Menus" chose "None" as opposed to "Select from list" and the problem went away. I don't understand the point of choosing menu items from "Select from list" if all it does is cause the error mentioned above.