Whilst trying to use Umazel Starter Kit on the latest version of Umbraco 7.6.3 I was getting the following Asp.Net Error:-

Exception Details: System.InvalidCastException: Specified cast is not valid.
switch ((int)currSection.TitleSize)

e.g.

Fix

Open umbracoSettings.config file usual in the Config directory of Umbraco.

Find:-

<EnablePropertyValueConverters>true</EnablePropertyValueConverters>

and change to 

<EnablePropertyValueConverters>false</EnablePropertyValueConverters>