Attempt by security transparent method \'PayPal.UserAgentHeader.get_OperatingSystemFriendlyName()\' to access security critical method \'System.Management.Management
After upgrading wpftoolkit 3.5 framework to 4.6.1 framework, the below Security rules in assemblyinfo.cs resolve the issue:
// added because of security transparency change in framework 4.0 [assembly: SecurityRules(SecurityRuleSet.Level1)]