We have a place we use a RadLightBox. Before the upgrade, we did not have any issues with it. Now we get the error "ItemsCounterFormatString should have one or two format placeholders!". I have done a solution wide search for ItemsCounterFormatString and it is not anywhere in the solution. It happens as soon as we try to do anything with the LightBox control. For instance:
memberLightBox = $find(
'<%= MemberLightBox.ClientID %>'
It will also happen if I make the control Client ID static and just access it that way.