Select2 dropdown An invalid form control with name='' is not focusable.

When dropdown field is required and empty and all other fields are correctly filled up, clicking a save button results in An invalid form control with name='dropdown' is not focusable. in js console, the form is not submitted, and nothing happens.

[sngrl]

This is my quick solution.

CSS-rule:

.select2-hidden-accessible[required] {
    display: block;
    height: 0;
    border: 1px solid transparent;
    margin-bottom: -2px;
}

Result on submit form which contains select2 element with required attribute:

[martincpt]

None of these solved this issue in my case. I have no such an item in the DOM like .select2-hidden-accessible[required]. Does anyone have up to date solution for this?