Ich habe vor ungefähr 2 Jahren eine Klassenbibliothek in .NET 2.0 für den Datenbankzugriff geschrieben und habe sie alle zusammen mit .NET 2.0, 3.0 und 3.5 verwendet.

Im aktuellen Projekt, an dem ich arbeite (bei dem es sich um eine .NET 4.0-Anwendung handelt), habe ich versucht, die alte treue Klassenbibliothek zu verwenden, und es ist die folgende Ausnahme aufgetreten:

System.InvalidOperationException was unhandled
  Message=An error occurred creating the form. See Exception.InnerException for details.
    The error is: Mixed mode assembly is built against version 'v2.0.50727' of the runtime
    and cannot be loaded in the 4.0 runtime without additional configuration information.
    Source=SchoolManager
  StackTrace:
       at SchoolManager.My.MyProject.MyForms.Create__Instance__[T](T Instance) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 190
       at SchoolManager.My.MyProject.MyForms.get_frmGeneric()
       at SchoolManager.My.MyApplication.OnCreateMainForm() in D:\Alex\Documents\Visual Studio 2008\Projects\School Manager\SchoolManager\My Project\Application.Designer.vb:line 35
       at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
       at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
       at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
       at SchoolManager.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: System.IO.FileLoadException
       Message=Mixed mode assembly is built against version 'v2.0.50727' of 
           the runtime and cannot be loaded in the 4.0 runtime without additional
           configuration information.
       Source=Dinofage.Data.XpressData
       StackTrace:
            at Dinofage.Data.XpressData.ExecuteSelectInternal(String selectCommand)
            at Dinofage.Data.XpressData.ExecuteSelect(String selectCommand)
            at SchoolManager.Academics.GetNewAdmissionCode(String academicYear) in D:\Alex\Documents\Visual Studio 2008\Projects\School Manager\SchoolManager\Modules\Academics.vb:line 89
            at SchoolManager.StudentDetail..ctor() in D:\Alex\Documents\Visual Studio 2008\Projects\School Manager\SchoolManager\UserControls\StudentDetail.vb:line 20
            at SchoolManager.frmGeneric.InitializeComponent() in D:\Alex\Documents\Visual Studio 2008\Projects\School Manager\SchoolManager\frmGeneric.Designer.vb:line 25
            at SchoolManager.frmGeneric..ctor()
       InnerException: 

Was könnte falsch sein und wie behebe ich das?