--- title: Sites-to-applications and routing breaking changes slug: cms-13/docs/sites-to-applications-and-routing-breaking-changes docTags: createdAt: 2026-07-30T20:22:07.220Z --- This article covers SiteDefinition-to-Application migration, URL routing, and UriSupport replacement breaking changes in CMS 13. ## Sites-to-applications migration CMS 13 replaces the `SiteDefinition` model with a new `Application` model. The following types are obsoleted: - `EPiServer.Web.SiteDefinition` – Obsolete in favor of `Application`. - `EPiServer.Web.SiteDefinitionEventArgs` – Obsolete in favor of `ApplicationEvent`. - `EPiServer.Web.SiteDefinitionUpdatedEventArgs` – Obsolete in favor of `ApplicationUpdatedEvent`. - `EPiServer.Web.ISiteDefinitionRepository` – Obsolete in favor of `IApplicationRepository`. A temporary shim layer loads applications as site definitions during the transition. - `EPiServer.Web.ISiteDefinitionResolver` – Obsolete in favor of `IApplicationResolver`. - `EPiServer.DataAbstraction.ISiteConfigurationRepository` – No longer used by CMS and obsoleted. No implementation is registered. ### Host configuration changes - Wildcard site host definition (`*`) is replaced with a default application. The `Application.IsDefault` property controls this behavior. - Database migration preserves existing sites, but the application model requires explicit "Default" host configuration. You may need to configure this manually in Admin > Config > Manage Applications. See [Application framework](docId\:woUIJII7WGJFp3ZrEuS7M) to understand available application types. ### Constructor and parameter changes When upgrading code that depends on `SiteDefinition` or `ISiteDefinitionResolver`: - Replace `ISiteDefinitionResolver` with `IApplicationResolver` in constructor injection. - `EPiServer.Cms.Shell.Search.ContentSearchProviderBase` – Changed constructor argument from `ISiteDefinitionResolver` to `IApplicationResolver`. - `EPiServer.Web.Routing.EditUrlResolver` – Methods accepting `SiteDefinition` as a parameter were obsoleted in favor of new overloads accepting `Application`. - `EPiServer.Web.SimpleAddressResolveContext` – The `SiteId` property is obsolete in favor of the `ApplicationName` property. ### Routing context changes - `EPiServer.Core.Routing.Pipeline.UrlResolverContext` – The `HostDefinition` property is obsolete in favor of the `ApplicationHost` property. - `EPiServer.Core.Routing.Pipeline.UrlGeneratorContext` – The `Host` property is obsolete in favor of `ApplicationHost`. The `CurrentHost` property is obsolete in favor of `CurrentApplicationHost`. - `EPiServer.Web.Routing.ContentRouteData` – New constructor parameter `Application`. Constructor parameter `HostDefinition` was replaced with `ApplicationHost`. - `EPiServer.Web.Routing.RoutingOptions` – Property `UsePrimaryHostForOutgoingUrls` was obsoleted. The system now always prefers primary hosts for URL generation (except in edit or preview mode with relative URLs). Property `UseEditHostForOutgoingMediaUrls` was obsoleted. Configure application host with type `Media` instead. ## UI URL segment change The default UI URL segment has changed from `/EPiServer` to `/Optimizely`. Module-specific URL segments have also been updated to remove EPiServer branding. The following module paths have changed: | CMS 12 module path | CMS 13 module path | | --------------------------------------------- | ----------------------------- | | `/EPiServer/EPiServer.Cms.UI.Admin/` | `/Optimizely/Settings/` | | `/EPiServer/EPiServer.Cms.UI.Settings/` | `/Optimizely/Profile/` | | `/EPiServer/EPiServer.Cms.UI.VisitorGroups/` | `/Optimizely/VisitorGroups/` | | `/EPiServer/EPiServer.Cms.UI.ContentManager/` | `/Optimizely/ContentManager/` | | `/EPiServer/EPiServer.Cms.Forms.UI/` | `/Optimizely/Forms/` | | `/EPiServer/EPiServer.Cms.UI.Webhooks/` | `/Optimizely/Webhooks/` | | `/EPiServer/EPiServer.Cms.UI.Credentials/` | `/Optimizely/Credentials/` | | `/EPiServer/Optimizely.Graph.Cms/` | `/Optimizely/GraphQL/` | | `/EPiServer/Optimizely.Cms.OpalChat/` | `/Optimizely/OpalChat/` | | `/EPiServer/EPiServer.Cms.TinyMce/` | `/Optimizely/TinyMce/` | | `/EPiServer/EPiServer.Cms.UI.Extensibility/` | `/Optimizely/Extensibility/` | | `/EPiServer/EPiServer.Cms.DamIntegration.UI/` | `/Optimizely/DamIntegration/` | Update any bookmarks, integrations, scripts, or hard-coded references that rely on the previous `/EPiServer/` URL format. ## UriSupport replacement The `EPiServer.UriSupport` class is obsolete. Resolve a singleton instance of `IUriSupport` from the DI container as a replacement. Members have been moved to dedicated classes: | Removed members | Replacement | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------- | | `HttpLocalhostUri`, `SiteDefinitionResolver`, `RemoveQueryStringDelimeter`, `Clear` | Removed (no longer used) | | `SiteUrl` | `EPiServer.Web.SiteDefinition.SiteUrl` | | `UIUrl`, `UtilUrl`, `ResolveUrlFromUIBySettings`, `ResolveUrlFromUIAsRelativeOrAbsolute`, `AbsoluteUrlFromUIBySettings`, `ResolveUrlFromUtilBySettings`, `AbsoluteUrlFromUtilBySettings` | `EPiServer.Web.UIPathResolver` | | `InternalUIUrl`, `InternalUtilUrl` | `EPiServer.Web.UIOption` | | `IsStringWellFormedUri`, `IsSchemeSpecified`, `Combine`, `BuildQueryString`, `AddQueryString`, `AddLanguageSelection`, `Split`, `SplitNoDelim`, `IsDataUri` | `EPiServer.Web.UriUtil` | | `AddValuesToCollection` | `System.Collections.Specialized.NameValueCollection` | | `EscapeUriSegments` | `EPiServer.UrlEncode` | ## EPiServer.Web routing changes - `EPiServer.Web.HttpRequestSupport` – Method `IsSystemDirectory` was removed in favor of `EPiServer.Web.UIPathResolver.IsSystemPath`. - `EPiServer.Web.PermanentLinkUtility` – Method `TryParseGuid` was removed in favor of `System.Guid.TryParse`. - `EPiServer.Web.PropertyControls.FileSortOrder` – Values `DateLastAccessed` and `DateLastAccessedDesc` were removed because they are no longer used. - `EPiServer.Web.Routing.AncestorReferencesLoader` – Parameter `contentEvents` was removed in the constructor. - `EPiServer.Web.Routing.RoutingConstants` – Constant `NodeKey` was removed because it is no longer used. - `EPiServer.Web.Routing.RoutingOptions` – Method `ConfigureForExternalTemplates` was removed in favor of `EPiServer.Web.Templating.TemplateOptions.ConfigureForExternalTemplates`. - `EPiServer.Web.UIPathResolver` – The parameterless constructor was removed. The static `Instance` method was obsoleted. Inject or retrieve the `UIPathResolver` singleton instance from the service container. ## IContentRouteEvents removal - `EPiServer.Web.Routing.IContentRouteEvents` – Interface removed. Use `IContentUrlResolverEvents` or `IContentUrlGeneratorEvents` instead. The individual events map as follows: - `CreatingVirtualPath` → `IContentUrlGeneratorEvents.GeneratingUrl` - `CreatedVirtualPath` → `IContentUrlGeneratorEvents.GeneratedUrl` - `RoutingContent` → `IContentUrlResolverEvents.ResolvingUrl` - `RoutedContent` → `IContentUrlResolverEvents.ResolvedUrl` ## EPiServer.Cms.AspNetCore routing - `EPiServer.Core.Routing.Pipeline.UrlResolverContext` – Property `RemainingPath` was removed in favor of property `RemainingSegments`. - `EPiServer.Core.Routing.Pipeline.UrlResolverContextExtensions` – Extension method `GetNextRemainingSegment` was removed in favor of method `GetNextSegment`. - `EPiServer.Cms.AspNetCore.Routing.ControllerActionEndpointSelectorPolicy` – Behavioral breaking change: when no action name constraint exists in the route, the "Index" method is selected first (if available) instead of the first valid endpoint by method sorting. - `System.Web.IHttpHandler` – This feature was removed. ## CMS routing behavioral changes - When a page has two language versions, and one language version is configured to use the other as a fallback, if the primary language version expires, CMS 13 displays the fallback language instead of showing a 404. - `EPiServer.Web.Routing.ContentRouter` – The `Instance` field was changed to a property. - `EPiServer.Web.Routing.RoutedContentEvaluationResult` – The `NotFound` and `OK` fields were changed to properties. - `EPiServer.Globalization.IUpdateCurrentLanguage` – Methods `UpdateLanguage` and `UpdateReplacementLanguage` were removed in favor of method `SetRoutedContent`. - `RouteArguments.MatchWildcardHost` – Obsolete. Use `MatchHost` instead.