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EPiServer.Core.TypeMismatchException when adding new PropertyList
Hello ThereseM
Some time ago, Optimizely released the Official List property. You can read more about it here:
https://world.optimizely.com/blogs/bartosz-sekula/dates/2023/1/official-list-property-support/
If the issue occurs only with new properties, it might be worth switching to this new approach—it could help resolve your problems.
Mar 22, 2025 18:21
I would recommend using IList<yourtype> and yourtype inheriting from BlockData.
You would have to write a scheduled job for migration of the content too.
Apr 02, 2025 16:58
We are running EPiServer CMS 12.32.3. We have serveral different PropertyLists on our site and have been using them for years.
But now I have run into an issue where I get a TypeMismatchException that craches the site when I start it the first time after adding a new PropertyList with a new PropertyDefinitionTypePlugIn. If I restart the site after the crash everything works as expected and I can use the PropertyList as intended. Has anyone else run into this issue? Does anyone know how I can fix it?
Below is an example of the error I get on the first startup after adding a brand new PropertyList.
2025-03-20 10:32:57.671 [Error] Hosting failed to startEPiServer.Framework.Initialization.InitializationException: Initialize action failed for Initialize on class EPiServer.Initialization.Internal.ModelSyncInitialization, EPiServer, Version=12.22.3.0, Culture=neutral, PublicKeyToken=8fe83dea738b45b7
---> EPiServer.Core.TypeMismatchException: Type 'System.Collections.Generic.IList`1[[CMS.Models.Blocks.Utbildning.StudieplanversionData, CMS.Models, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]' could not be mapped to a PropertyDefinitionType
at EPiServer.DataAbstraction.RuntimeModel.Internal.PropertyDefinitionSynchronizer.ResolveType(PropertyDefinitionModel model)
at EPiServer.DataAbstraction.RuntimeModel.Internal.PropertyDefinitionSynchronizer.CreatePropertyDefinition(PropertyDefinitionModel model, Int32 contentTypeID)
at EPiServer.DataAbstraction.RuntimeModel.Internal.ContentTypeModelRegister.CommitProperties(Boolean deleteUnusedTypes)
at EPiServer.DataAbstraction.RuntimeModel.Internal.ContentTypeModelScanner.Sync(Boolean forceCommit)
at EPiServer.Initialization.Internal.ModelSyncInitialization.Initialize(InitializationEngine context)
at EPiServer.Framework.Initialization.Internal.ModuleNode.<>c__DisplayClass4_0.<Initialize>b__0()
at EPiServer.Framework.Initialization.Internal.ModuleNode.Execute(Action a, String key)
at EPiServer.Framework.Initialization.Internal.ModuleNode.Initialize(InitializationEngine context)
at EPiServer.Framework.Initialization.InitializationEngine.InitializeModules()
--- End of inner exception stack trace ---
at EPiServer.Framework.Initialization.InitializationEngine.InitializeModules()
at EPiServer.Framework.Initialization.InitializationEngine.ExecuteTransition(Boolean continueTransitions)
at EPiServer.Framework.Initialization.InitializationEngine.Initialize()
at EPiServer.Hosting.Internal.EPiServerFrameworkHost.StartAsync(CancellationToken cancellationToken)
at Microsoft.Extensions.Hosting.Internal.Host.<StartAsync>b__15_1(IHostedService service, CancellationToken token)
at Microsoft.Extensions.Hosting.Internal.Host.ForeachService[T](IEnumerable`1 services, CancellationToken token, Boolean concurrent, Boolean abortOnFirstException, List`1 exceptions, Func`3 operation)