This error showed up on a production (not yet live) server.
It's troubling because the build was showing no issues for a week prior but there has been an extensive content entry on the Catalog and CMS side.
[TypeMismatchException: The backing type 'EPiServer.Core.PropertyDate' is not a registered PropertyDefinitionType]
EPiServer.DataAbstraction.RuntimeModel.Internal.PropertyDefinitionSynchronizer.ResolveType(PropertyDefinitionModel model) +341
EPiServer.DataAbstraction.RuntimeModel.Internal.ContentTypeModelRegister.ValidateChangeOfModelType(PropertyDefinitionModel propertyModel, String modelName) +66
EPiServer.DataAbstraction.RuntimeModel.Internal.ContentTypeModelRegister.SetStateForPropertyDefinitionModels(ContentTypeModel model) +137
EPiServer.DataAbstraction.RuntimeModel.Internal.ContentTypeModelRegister.<AnalyzeProperties>b__14_0(ContentTypeModel model) +59
System.Threading.Tasks.<>c__DisplayClass31_0`2.<ForEachWorker>b__0(Int32 i) +63
System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) +18
System.Threading.Tasks.<>c__DisplayClass176_0.<ExecuteSelfReplicating>b__0(Object ) +199
It appears it could be something related to the data entry that is creating corrupted data and resulting issue. I say this because I’ve ran an old release against the production dbs and get the same issue in my local environment.
If anyone has had experience with this or solved an issue like this your comments are greatly appreciated.
This issue was solved by running a SQL insert command on the tblPropertyDefinitionType table to enter a supporting property type for PropertyDate.
It's still a mystery as to why this wasn't discovered during local development and made it's way all the way to production and seemed to go down during a weekend when there was no usage of the not live yet site.