Symptoms

 We got this issue when installing
The following exception occurred:
An attempt was made to load an assembly from a network location which would have caused the assembly to be sandboxed in previous versions of the .NET Framework. This release of the .NET Framework does not enable CAS policy by default, so this load may be dangerous. If this load is not intended to sandbox the assembly, please enable the loadFromRemoteSources switch. See http://go.microsoft.com/fwlink/?LinkId=155569 for more information.

Could not load file or assembly 'file:///E:k2K2 Installation Package 4.6.9K2 blackpearl 4.6.9 (4.1)K2 blackpearl 4.6.9 (4.12060.1640.1)InstallationLicensingx64SourceCode.HostServerInterfaces.dll' or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)
StackTrace: at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMarkand stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMarkand stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMarkand stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
at System.Reflection.RuntimeAssembly.InternalLoadFrom(String assemblyFile, Evidence securityEvidence, Bytee] hashValue, AssemblyHashAlgorithm hashAlgorithm, Boolean forIntrospection, Boolean suppressSecurityChecks, StackCrawlMarkand stackMark)
at System.Reflection.Assembly.LoadFrom(String assemblyFile)
at SourceCode.Install.Common.Classes.SC_Licensing.GetLicenseAssembly()
at SourceCode.Install.Common.Classes.SC_Licensing.Load(String sPath)
at SourceCode.SetupManager.UI.Panels.LicensePanel.PopulateUi()
at SourceCode.SetupManager.UI.Panels.LicensePanel.ActivatePanel()
at SourceCode.SetupManager.Main.navigateNext()
 

Diagnoses

It seems the dll is locked
 

Resolution 

Find the dll then unlock it.

Go to the 'file:///E:k2K2 Installation Package 4.6.9K2 blackpearl 4.6.9 (4.1)K2 blackpearl 4.6.9 (4.12060.1640.1)InstallationLicensingx64SourceCode.HostServerInterfaces.dll' dll then right click it for properties then click unlock near the bottom of the properties window