2.1.86 [HTML5:2014] Section 4.10.21.1 Definitions

V0196: The setCustomValidity function is not supported

The specification states:

 4.10.21.1 Definitions
     ...
     An element can have a custom validity error message defined. Initially, an element 
     must have its custom validity error message set to the empty string. When its value 
     is not the empty string, the element is suffering from a custom error. It can be set 
     using the setCustomValidity() method. ...

IE9 Mode, IE8 Mode, IE7 Mode, and IE5 (Quirks) Mode (All versions)

The setCustomValidity function is not supported.