Clear Validation Error On TextBox TextChanged event WPF

WPF > Validation > ClearInvalid

Removes all ValidationError objects from the specified BindingExpression object.

Example

this.TextChanged += TextBox_TextChanged;

void TextBox_TextChanged(object sender, TextChangedEventArgs e)

{

     Validation.ClearInvalid(((TextBox)sender).GetBindingExpression(TextBox.TextProperty));

}