[html] An invalid form control with name='' is not focusable

Yet another possibility if you're getting the error on a checkbox input. If your checkboxes use custom CSS which hides the default and replaces it with some other styling, this will also trigger the not focusable error in Chrome on validation error.

I found this in my stylesheet:

input[type="checkbox"] {
    visibility: hidden;
}

Simple fix was to replace it with this:

input[type="checkbox"] {
    opacity: 0;
}