This means you could instead select it with select='.classname' and it would grab approach works too of course, because selectors defined by loaded directives don't need to be checked against the DOM schema.
Alternatively, ng-content's select attribute can take other CSS selector types than just elements.
As of 2.0.1, there are two values you can add to this array: CUSTOM_ELEMENTS_SCHEMA, which allows elements and properties with hyphens, and NO_ERRORS_SCHEMA, which suppresses all schema errors. This property helps configure the document schema, which defines which elements and properties are valid and can be bound to. To expand a bit on that answer, there are two main fixes: FYI, there's a good response by over at #11659.
