Hi,

I'd say that does sound surprising as there shouldn't be any changes in the schema to update. The way smooth deploy should work is that a copy of the existing web app and database (in read-only mode) is made. Live web traffic is then pointed at the read-only copy of the site while the new codebase is deployed to the original web app, pointed at the original read/write instance of the database. The read-only version of the site is a copy of what was already there so no schema update should be required. Any changes which have been made in the codebase as part of the new release which require a schema update would be deployed to the read/write version of the site so shouldn't have any issues updating the schema.

You could potentially switch off schema updates when the DB is in read-only mode by doing something like this in your startup.cs:

services.Configure<DataAccessOptions>(o => o.UpdateDatabaseSchema = ServiceLocator.Current.GetInstance<IDatabaseMode>().DatabaseMode.Equals(DatabaseMode.ReadWrite));

I've not checked whether that would work but I suspect, even if it did, you'd just end up with an error telling you that the schema needs updating.

If it's practical to do so, you could deploy using smooth deploy in read/write mode though you'd need to ensure you're happy to lose any changes which are made to the database during the deploy (e.g. content changes, form submissions, etc.).

Great suggestion, Paul. You were also correct that it lead to another error down the line. In addition, changing the database mode to "ReadWrite" gave us a more specific error: 

warn: EPiServer.DataAbstraction.RuntimeModel.Internal.ContentTypeModelRegister[0]
     Changes in the model were ignored because its version(0.0.0.0) is lower than version in the database(0.5).

One thing that caught our attention this morning is the following line from this (https://docs.developers.optimizely.com/digital-experience-platform/docs/smooth-deploy) page:

Smooth deployment is available for Optimizely Content Management System (CMS) only.

This raised our eyebrows because we are attempting to implement smooth deploy on a commerce site. In my last response, I only gave partial output. However, the full stack-trace shows that our error is thrown from a mediachase namespace:

EPiServer.Framework.Initialization.InitializationException: 'Initialize action failed for Initialize on class EPiServer.Initialization.Internal.ModelSyncInitialization, EPiServer, Version=12.12.1.0, Culture=neutral, PublicKeyToken=8fe83dea738b45b7'
   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>d__12.MoveNext()
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.<RunAsync>d__4.MoveNext()
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.<RunAsync>d__4.MoveNext()
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.Run(IHost host)
   at ProductPlatform.Program.Main(String[] args) in C:\<localpath>\Program.cs:line 15
Inner exception: NotSupportedException: Database writes are blocked since the application is set to ReadOnly mode. ReadOnly mode is set either by the 'databaseMode' attribute on the 'episerver.dataStore' section or by the 'episerver:DatabaseMode' setting under the 'appSettings' section.
   at Mediachase.Data.Provider.DataService.ThrowIfReadonlyMode()
   at Mediachase.MetaDataPlus.Configurator.MetaDataPlusDatabase.UpdateMetaField(MetaDataContext context, Int32 metaFieldId, String fieldNamespace, String friendlyName, String description, Object tag)
   at Mediachase.MetaDataPlus.Configurator.MetaField.set_Description(String value)
   at EPiServer.Commerce.Catalog.Provider.Construction.CatalogContentScannerExtension.UpdateMetaField(PropertyDefinitionModel propertyDefinitionModel, MetaField metaField)
   at EPiServer.Commerce.Catalog.Provider.Construction.CatalogContentScannerExtension.CreateOrUpdateMetaField(MetaClass metaClass, PropertyDefinitionModel propertyDefinitionModel)
   at EPiServer.Commerce.Catalog.Provider.Construction.CatalogContentScannerExtension.AssignModelPropertiesToMetaClass(MetaClass metaClass, IEnumerable`1 propertyDefinitionModels)
   at EPiServer.Commerce.Catalog.Provider.Construction.CatalogContentScannerExtension.AssignValuesToProperties(ContentTypeModel contentTypeModel)
   at EPiServer.DataAbstraction.RuntimeModel.Internal.ContentTypeModelScanner.AssignValuesToProperties(ContentTypeModel modelType)
   at EPiServer.DataAbstraction.RuntimeModel.Internal.ContentTypeModelScanner.AddModel(Type type)
   at EPiServer.DataAbstraction.RuntimeModel.Internal.ContentTypeModelScanner.RegisterModels()
   at EPiServer.Initialization.Internal.ModelSyncInitialization.Initialize(InitializationEngine context)
   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()

Are we restricted from implementing smooth deploy because its a commerce site?