Hi guys

I am not sure if this is a bug but on one of my recent recent site build on 6 SP1 I tend to get the following error on some cold start (e.g. first visit of the day).

Since the site was upgraded from 6.0 to 6.0.23 at first I thought it was an issue with the upgrading process so I re-built the site on a clean install (i.e. from 6.0.23 web installer) but it keeps on sometimes appearing.

Any thought on what might cause this is welcome.

Log extract:

Event ID: 410
Event type: Error
Event time: 5/17/2012 2:41:33 PM
Source: Application_Error
Event code: EXCEPTION
User ID: 65
User name: public
IP address: ::1
Node ID: 3
Document name: Home

Description: Message: Could not load file or assembly 'FSharp.Core, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.
Stack Trace:
at System.ModuleHandle.ResolveType(RuntimeModule module, Int32 typeToken, IntPtr* typeInstArgs, Int32 typeInstCount, IntPtr* methodInstArgs, Int32 methodInstCount, ObjectHandleOnStack type)
at System.ModuleHandle.ResolveTypeHandleInternal(RuntimeModule module, Int32 typeToken, RuntimeTypeHandle[] typeInstantiationContext, RuntimeTypeHandle[] methodInstantiationContext)
at System.Reflection.RuntimeModule.ResolveType(Int32 metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments)
at System.Reflection.CustomAttribute.FilterCustomAttributeRecord(CustomAttributeRecord caRecord, MetadataImport scope, Assembly& lastAptcaOkAssembly, RuntimeModule decoratedModule, MetadataToken decoratedToken, RuntimeType attributeFilterType, Boolean mustBeInheritable, Object[] attributes, IList derivedAttributes, RuntimeType& attributeType, IRuntimeMethodInfo& ctor, Boolean& ctorHasParameters, Boolean& isVarArg)
at System.Reflection.CustomAttribute.GetCustomAttributes(RuntimeModule decoratedModule, Int32 decoratedMetadataToken, Int32 pcaCount, RuntimeType attributeFilterType, Boolean mustBeInheritable, IList derivedAttributes, Boolean isDecoratedTargetSecurityTransparent)
at System.Reflection.CustomAttribute.GetCustomAttributes(RuntimeAssembly assembly, RuntimeType caType)
at System.Reflection.RuntimeAssembly.GetCustomAttributes(Boolean inherit)
at System.Web.UI.AssemblyCache.GetAjaxFrameworkAssemblyAttribute(Assembly assembly)
at System.Web.UI.ScriptManager.get_DefaultAjaxFrameworkAssembly()
at System.Web.UI.ScriptManager..ctor()
at ASP.cmspages_portaltemplate_aspx.__BuildControlmanScript()
at ASP.cmspages_portaltemplate_aspx.__BuildControlplcManagers()
at ASP.cmspages_portaltemplate_aspx.__BuildControlform()
at ASP.cmspages_portaltemplate_aspx.__BuildControlTree(cmspages_portaltemplate_aspx __ctrl)
at ASP.cmspages_portaltemplate_aspx.FrameworkInitialize()
at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest()
at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context)
at System.Web.UI.Page.ProcessRequest(HttpContext context)
at ASP.cmspages_portaltemplate_aspx.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Site name: [omitted]
Machine name: [omitted]
Event URL: /home.aspx
URL referrer:
User agent: Mozilla/5.0 (Windows NT 6.0) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.46 Safari/536.5