While doing some development on SharePoint solution deployment I
encountered a strange behaviour. The following code gave me the
"FormatException:Guid should contain 32 digits with 4 dashes"
error:
SPFarm.Local.Solution["demo.wsp"].DeployedWebApplications;
Strange as I'm not even using a GUID in my code here. So a
little breaking down led me to the conclusion that if you call the
DeployedWebApplications property on a solution that is globally
deployed you get this error.