可能是重复的问题:
安装MVC 4 Beta时出现并行安装错误
我正在开发一个MVC3应用程序。 我想开始开发一个MVC4应用程序。 但是,在安装MVC 4后(非beta版本),MVC 3应用程序停止工作,出现一些dll冲突错误。 其中一种错误是这样的:
The type 'System.Web.Helpers.Json' exists in both 'c:\Windows\Microsoft.NET\assembly\GAC_MSIL \System.Web.Helpers\v4.0_2.0.0.0__31bf3856ad364e35\System.Web.Helpers.dll' and 'c:\Windows \Microsoft.NET\assembly\GAC_MSIL\System.Web.Helpers \v4.0_1.0.0.0__31bf3856ad364e35\System.Web.Helpers.dll' `at System.Web.Compilation.AssemblyBuilder.Compile()
at System.Web.Compilation.BuildProvidersCompiler.PerformBuild()
at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath)
at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate)
at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate)
at System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound)
at System.Web.Compilation.BuildManager.GetObjectFactory(String virtualPath, Boolean throwIfNotFound)
at System.Web.Mvc.BuildManagerWrapper.System.Web.Mvc.IBuildManager.FileExists(String virtualPath)
at System.Web.Mvc.BuildManagerViewEngine.FileExists(ControllerContext controllerContext, String virtualPath)
at System.Web.Mvc.VirtualPathProviderViewEngine.GetPathFromGeneralName(ControllerContext controllerContext, List`1 locations, String name, String controllerName, String areaName, String cacheKey, String[]& searchedLocations)
at System.Web.Mvc.VirtualPathProviderViewEngine.GetPath(ControllerContext controllerContext, String[] locations, String[] areaLocations, String locationsPropertyName, String name, String controllerName, String cacheKeyPrefix, Boolean useCache, String[]& searchedLocations)
at System.Web.Mvc.VirtualPathProviderViewEngine.FindView(ControllerContext controllerContext, String viewName, String masterName, Boolean useCache)
at System.Web.Mvc.ViewEngineCollection.<>c__DisplayClassc.<FindView>b__b(IViewEngine e)
at System.Web.Mvc.ViewEngineCollection.Find(Func`2 lookup, Boolean trackSearchedPaths)
at System.Web.Mvc.ViewEngineCollection.Find(Func`2 cacheLocator, Func`2 locator)
at System.Web.Mvc.ViewEngineCollection.FindView(ControllerContext controllerContext, String viewName, String masterName)
at System.Web.Mvc.ViewResult.FindView(ControllerContext context)
at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<>c__DisplayClass1e.<InvokeActionResultWithFilters>b__1b()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<>c__DisplayClass1e.<InvokeActionResultWithFilters>b__1b()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)`
这个问题应该如何解决?