The unofficial way to fix the issue is to run this SQL snippet in context of CMS database

UPDATE tblContentType
SET modelType = 'EPiServer.Core.CampaignFolder, EPiServer.Business.Commerce, Version=8.6.1.431, Culture=neutral, PublicKeyToken=8fe83dea738b45b7'
WHERE [Name] like 'SysCampaignFolder'

Untested by me. 

Hi Quan,

I had found the article that the snippet is from but was unsure whether it would be useful due to the older versions in play.

I've just ran it against the DB and it just returns the same error but with a different version number.

Could not create instance of content type "SysCampaignFolder" since it has an invalid .NET class associated: EPiServer.Core.CampaignFolder, EPiServer.Business.Commerce, Version=8.6.1.431, Culture=neutral, PublicKeyToken=8fe83dea738b45b7

Any other ideas? Has the SysCampaignFolder been phased out in the current packages or anything like that?

Hmm, now I look into it, it looks like the content type was removed and the root was registered automatically. So can you try to back up your databases and try to delete that content type?

Hi Quan,

I deleted the content type from the database however, it seems like that results in an error -

Value cannot be null.
Parameter name: contentType
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.ArgumentNullException: Value cannot be null.
Parameter name: contentType

Source Error: 


[No relevant source lines]

Source File: c:\Users\james.johnson\AppData\Local\Temp\Temporary ASP.NET Files\vs\408fcc3f\cfebce5f\App_global.asax.6usl8oko.0.cs    Line: 0 

Stack Trace: 


[ArgumentNullException: Value cannot be null.
Parameter name: contentType]
   EPiServer.Construction.Internal.ContentFactory.CreateContent(ContentType contentType, BuildingContext buildingContext) +459
   EPiServer.Commerce.Catalog.Provider.Construction.Internal.CatalogContentFactory.CreateContent(ContentType contentType, BuildingContext buildingContext) +153
   EPiServer.DataAccess.Internal.ContentDB.CreateContent(ContentType contentType) +14
   EPiServer.DataAccess.Internal.ContentLoadDB.LoadContentInternal(ContentReference contentLink, Int32 languageBranchId, DbDataReader reader) +279
   EPiServer.DataAccess.Internal.<>c__DisplayClass2_0.<Load>b__0() +286
   EPiServer.Data.Providers.Internal.<>c__DisplayClass31_0`1.<Execute>b__0() +58
   EPiServer.Data.Providers.SqlTransientErrorsRetryPolicy.Execute(Func`1 method) +70
   EPiServer.Core.<>c__DisplayClass121_0.<LoadContentFromCacheOrRepository>b__0() +35
   EPiServer.Framework.Cache.ObjectInstanceCacheExtensions.ReadThroughWithWait(IObjectInstanceCache cache, String cacheKey, Func`1 readValue, Func`2 evictionPolicy) +981
   EPiServer.Core.Internal.ContentInstanceCache.ReadThrough(ContentReference contentLink, String selectedLanguage, Func`1 readValue) +107
   EPiServer.Core.ContentProvider.LoadContentFromCacheOrRepository(ContentReference contentreference, ILanguageSelector selector) +602
   EPiServer.Core.Internal.ProviderPipelineImplementation.GetItem(ContentProvider provider, ContentReference contentLink, LoaderOptions loaderOptions) +309
   EPiServer.Core.Internal.DefaultContentLoader.TryGet(ContentReference contentLink, LoaderOptions loaderOptions, T& content) +574
   EPiServer.Core.Internal.DefaultContentLoader.TryGet(Guid contentGuid, T& content) +99
   EPiServer.Core.Internal.DefaultContentRepository.TryGet(Guid contentGuid, T& content) +85
   EPiServer.DataAbstraction.Internal.DefaultContentRootService.Register(String rootName, Guid contentRootId, ContentReference parentRoot) +190
   EPiServer.Commerce.Initialization.InitializationModule.RegisterContentRoots(InitializationEngine context) +428
   EPiServer.Commerce.Initialization.InitializationModule.Initialize(InitializationEngine context) +220
   EPiServer.Framework.Initialization.Internal.ModuleNode.Execute(Action a, String key) +58
   EPiServer.Framework.Initialization.Internal.ModuleNode.Initialize(InitializationEngine context) +123
   EPiServer.Framework.Initialization.InitializationEngine.InitializeModules() +248

[InitializationException: Initialize action failed for Initialize on class EPiServer.Commerce.Initialization.InitializationModule, EPiServer.Business.Commerce, Version=12.5.0.0, Culture=neutral, PublicKeyToken=8fe83dea738b45b7]
   EPiServer.Framework.Initialization.InitializationEngine.InitializeModules() +774
   EPiServer.Framework.Initialization.InitializationEngine.ExecuteTransition(Boolean continueTransitions) +194
   EPiServer.Framework.Initialization.InitializationModule.EngineExecute(HostType hostType, Action`1 engineAction) +876
   EPiServer.Framework.Initialization.InitializationModule.FrameworkInitialization(HostType hostType) +225
   EPiServer.Global..ctor() +42
   ASP.global_asax..ctor() in c:\Users\james.johnson\AppData\Local\Temp\Temporary ASP.NET Files\vs\408fcc3f\cfebce5f\App_global.asax.6usl8oko.0.cs:0

[TargetInvocationException: Exception has been thrown by the target of an invocation.]
   System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0
   System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +139
   System.Activator.CreateInstance(Type type, Boolean nonPublic) +105
   System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark) +1431
   System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) +184
   System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture) +27
   System.Web.HttpRuntime.CreateNonPublicInstance(Type type, Object[] args) +79
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +262
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +341

[HttpException (0x80004005): Exception has been thrown by the target of an invocation.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +523
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +107
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +688

There must still be some reference in there somewhere, are there any other tables you can think of that I'd need to check/delete some?

Cheers

I think you need to delete the content in tblContent which points to that deleted content type, but it should have the reference that prevents you from deleting the content type if a content of that type still exists.

I'm not sure what to suggest you now, it's probably the time to restore the databases and contact developer support service for help .

Ok, I'll do that then. Thanks for your help QM.