NPOI dll (third party excel writer dll)....System.Security.SecurityException: That assembly does not allow partially trusted callers

Question

I had developed portal on Asp.net mvc framework.I had hosted this site at godaddy hosting.I had a great problem on integrating third party dll i.e. NPOI (excel writer dll).It dispaly following error.

Security Exception

**Description**: *The application attempted to perform an operation not allowed by the security policy.  To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file.*

**Exception Detail*s**:* System.Security.SecurityException: That assembly does not allow partially trusted callers.

   **Source Error:**

    *An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.*

Stack Trace:

[SecurityException: That assembly does not allow partially trusted callers.]
   ETravel.Web.Modules.Travel.Controllers.Admin.ReportController.TravelTaxList() in ReportController.cs:853
   lambda_method(ExecutionScope , ControllerBase , Object[] ) +39
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +17
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +178
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +24
   System.Web.Mvc.<>c__DisplayClassa.<InvokeActionMethodWithFilters>b__7() +52
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +254
   System.Web.Mvc.<>c__DisplayClassc.<InvokeActionMethodWithFilters>b__9() +19
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +254
   System.Web.Mvc.<>c__DisplayClassc.<InvokeActionMethodWithFilters>b__9() +19
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +254
   System.Web.Mvc.<>c__DisplayClassc.<InvokeActionMethodWithFilters>b__9() +19
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +192
   System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +399
   System.Web.Mvc.Controller.ExecuteCore() +126
   System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +27
   System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +7
   System.Web.Mvc.MvcHandler.ProcessRequest(HttpContextBase httpContext) +151
   System.Web.Mvc.MvcHandler.ProcessRequest(HttpContext httpContext) +57
   System.Web.Mvc.MvcHandler.System.Web.IHttpHandler.ProcessRequest(HttpContext httpContext) +7
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +181
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

To solve this problem i had added this code line in web.config file.

<compilation debug="true">
   <assemblies>
.....................    .............
        <add assembly ="NPOI, Version=1.2.1.0, Culture=neutral, PublicKeyToken=0df73ec7942b34e1"/>
        <add assembly="NPOI.POIFS, Version=1.2.1.0, Culture=neutral, PublicKeyToken=0df73ec7942b34e1"/>
        <add assembly ="NPOI.HPSF, Version=1.2.1.0, Culture=neutral, PublicKeyToken=0df73ec7942b34e1"/>
        <add assembly ="NPOI.Util, Version=1.2.1.0, Culture=neutral, PublicKeyToken=0df73ec7942b34e1"/>
   </assemblies>
  </compilation>

And [assembly: AllowPartiallyTrustedCallers()] to Assemblyinfo.cs. But worn't work.what's the main problem and what is the solution???Pls help me...

Answer 1

No, it's NPOI that needs to allow partially trusted callers. It's probably doing something under-the-covers that won't work in a medium trust environment.

Looking at the NPOI website it looks like it was updated to run in medium trust environments towards the end of last year, but that was after the 1.2.1 release. You should try the latest version, 1.2.3 beta, to see if that update has made it in and if that will fix it for you.