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Model accessor arguments are not supported.


When I log into Edit Mode in the CMS, I'm seeing an XHR request to 


which is resulting in a YSOD and balking all JavaScript in the editor. The text of the error is below.

What might be causing it? 

The JavaScript call stack isn't very helpful. It's a bunch of anonymous functions and callbacks in dojo.js, epi.js and widgets.js. The application is based on the Alloy MVC sample site.





Server Error in '/' Application.

Model accessor arguments are not supported
Parameter name: arguments

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.ArgumentException: Model accessor arguments are not supported
Parameter name: arguments

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: 

[ArgumentException: Model accessor arguments are not supported
Parameter name: arguments]
   EPiServer.Cms.Shell.UI.ContentDataModelAccessorCreator.Create(Dictionary`2 arguments) +669
   EPiServer.Shell.UI.Rest.MetadataStore.GetModelAccessor(String modelAccessorParam, Type t) +231
   EPiServer.Shell.UI.Rest.MetadataStore.Get(String type, String modelAccessor) +53
   lambda_method(Closure , ControllerBase , Object[] ) +179
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +261
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +39
   System.Web.Mvc.<>c__DisplayClass13.<InvokeActionMethodWithFilters>b__10() +124
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +309
   System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +854224
   EPiServer.Shell.Services.Rest.RestControllerBase.ExecuteCore() +241
   System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +334
   EPiServer.Shell.Services.Rest.RestHttpHandler.ProcessRequest(HttpContextBase httpContext) +274
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +913
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +165


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.18045


Aug 06, 2013 10:31

The issue was, I'd implemented an HTTPModule that enforces lowercase URLs by 301 redirecting the user if the URL contains an uppercase character. 

This was interfering with the EPiServer UI. The fix was to make the module ignore the EPiServer URLs



Aug 06, 2013 12:33
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