VC2064: <parameter> attribute value isn't valid

An attribute's value isn't valid: required="yes", expanded="yes" on a <parameter-group>, min="ten", min more than max, an aspect-ratio that isn't width:height, a pattern that isn't a regular expression, a separator longer than one character, a {...} placeholder other than {target}, or a toolbar action formatted text can't hold.

How to fix

Use a value of the kind the attribute takes. The message says which.