The Dropdown Search Widget doesn't have the Mandatory property, so its not possible to do the built-in form validation and have the same behavior as the others input widgets - validation has to be developed and error message implemented manually.
This is much needed and would improve the user experience.
The overhead to implement this now is somewhat prohibitive.
Facing the same challenge! Cannot get required field error message as easily as other widgets.
I can't believe this doesn't have more votes. This is a painful thing to configure every time you use the search dropdown. This needs more votes!
Commenting to bump this up
I have to implement custom validation for each dropdown search separatelyHaving a mandatory property would save a lot of steps