ICustomTypeDescriptor, is an interface and cannot be constructed. Are you missing a type mapping? - Progress Community

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ICustomTypeDescriptor, is an interface and cannot be constructed. Are you missing a type mapping?

This article provides information for resoling a problem with Sitefinity startup. At startup an error ICustomTypeDescriptor, is an interface and cannot be constructed shows up and the site is stuck.

Aug 18, 2021
Knowledge

Title

ICustomTypeDescriptor, is an interface and cannot be constructed. Are you missing a type mapping?

URL Name

icustomtypedescriptor-is-an-interface-and-cannot-be-constructed-are-you-missing-a-type-mapping

Article Number

000156690

Environment

Product: Sitefinity Versions: 10.x, 11.x, 12.x, 13.x, 14.x, 15.x OS: All supported OS versions Database: All supported Microsoft SQL Server versions

Question/Problem Description

Suddenly one web server started throwing the error at the bottom of this message. It started on one page, then propagated to every other page request coming in. It didn't happen on the other web server. Doing an IIS reset on the affected server did not work; only copying the web files from server 1 to server 2 and then performing an IIS reset resolved the issue. Not able to reproduce locally or on the web servers.

Full error text from the Sitefinity logs: The current type, System.ComponentModel.ICustomTypeDescriptor, is an interface and cannot be constructed. Are you missing a type mapping?

Steps to Reproduce

Clarifying Information

Error Message

Message: HandlingInstanceID: 887b36c9-56e7-4257-a4f9-ef61ee7b450c An exception of type 'Telerik.Microsoft.Practices.Unity.ResolutionFailedException' occurred and was caught. ----------------------------------------------------------------------------------------------------------- 11/ 23/2017 05:35:02 Type : Telerik.Microsoft.Practices.Unity.ResolutionFailedException, Telerik.Sitefinity.Utilities, Version=10.1.6521.0, Culture=neutral, PublicKeyToken=b28c218413bdf563 Message : Resolution of the dependency failed, type = "System.ComponentModel.ICustomTypeDescriptor", name = "Telerik.Sitefinity.Mvc.Proxy.IControllerSettings". Exception occurred while: while resolving. Exception is: InvalidOperationException - The current type, System.ComponentModel.ICustomTypeDescriptor, is an interface and cannot be constructed. Are you missing a type mapping? ----------------------------------------------- At the time of the exception, the container was: Resolving System.ComponentModel.ICustomTypeDescriptor,Telerik.Sitefinity.Mvc.Proxy.IControllerSettings Source : Telerik.Sitefinity.Utilities Help link : TypeRequested : ICustomTypeDescriptor NameRequested : Telerik.Sitefinity.Mvc.Proxy.IControllerSettings Data : System.Collections.ListDictionaryInternal TargetSite : System.Object DoBuildUp(System.Type, System.Object, System.String, System.Collections.Generic.IEnumerable`1[Telerik.Microsoft.Practices.Unity.ResolverOverride]) HResult : -2146233088 Stack Trace : at Telerik.Microsoft.Practices.Unity.UnityContainer.DoBuildUp(Type t, Object existing, String name, IEnumerable`1 resolverOverrides) at Telerik.Microsoft.Practices.Unity.UnityContainer.DoBuildUp(Type t, String name, IEnumerable`1 resolverOverrides) at Telerik.Microsoft.Practices.Unity.UnityContainerExtensions.Resolve[T](IUnityContainer container, String name, ResolverOverride[] overrides) at System.ComponentModel.TypeDescriptor.TypeDescriptionNode.DefaultTypeDescriptor.System.ComponentModel.ICustomTypeDescriptor.Ge tProperties() at System.ComponentModel.TypeDescriptor.GetPropertiesImpl(Object component, Attribute[] attributes, Boolean noCustomTypeDesc, Boolean noAttributes) at Telerik.Sitefinity.Mvc.Proxy.ControllerSettings.SetDefaultControllerValues() at Telerik.Sitefinity.Mvc.Proxy.MvcControllerProxy.get_Settings() at Telerik.Sitefinity.Mvc.ControllerActionInvoker.DeserializeControllerProperties(MvcProxyBase proxyControl) at Telerik.Sitefinity.Mvc.ControllerActionInvoker.TryInvokeAction(MvcProxyBase proxyControl, String& output) at Telerik.Sitefinity.Mvc.Proxy.MvcControllerProxy.OnPreRender(EventArgs e) at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Defect Number

Enhancement Number

Cause

The exact cause is not known at this time.

Resolution

The problem occurs randomly and is solved by a different action for different sites. Perform the resolution action in this order until the problem is gone.
Resolution Action 1:
1. Edit web.config
2. in <compilation> element set debug="false" explicitly <compilation debug="false". Modify also tag optimizeCompilations="true" to be false: optimizeCompilations="false".
3. Save changes to web.config (note saving web.config will restart the site)

The setting affects compilation and once applied affects the compilation of site resources among which .cshtml which must be the trigger for the problem. They are compiled once and added to the site`s /bin folder in assembly SitefinityWebApp.ResourcePackages.xxxxxxx.dll
4. compile/build the site after setting optimizeCompilations="false". Take the /bin folder and deploy it to production server.
If multiple developers are compiling/building the site ensure all of them have optimizeCompilations="false" and have performed compiling/building of the codebase afterwards.

Resolution Action 2:
1. Backup the /bin folder of the site
2. Copy the /bin folder from a newly created Sitefinity site on the same version and replace the files in the /bin folder with those from the newly created Sitefinity site.

Resolution Action 3:
1. Disable the precompilation of razor views by following KB article: How to turn off precompilation of Razor views in Sitefinity Feather

Workaround

Notes

Keyword Phrase

Last Modified Date

3/18/2025 12:50 PM

Sitefinity CloudSitefinity Bugs & IssuesSitefinity Front & Back-End DevelopmentSitefinity UpgradingSitefinity General Discussions

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ICustomTypeDescriptor, is an interface and cannot be constructed. Are you missing a type mapping? - Progress Community