diff --git a/Emby.Server.Implementations/Channels/ChannelManager.cs b/Emby.Server.Implementations/Channels/ChannelManager.cs
index 3d97a6ca8d..57684a4298 100644
--- a/Emby.Server.Implementations/Channels/ChannelManager.cs
+++ b/Emby.Server.Implementations/Channels/ChannelManager.cs
@@ -540,18 +540,18 @@ namespace Emby.Server.Implementations.Channels
                 {
                     IncludeItemTypes = new[] { nameof(Channel) },
                     OrderBy = new[] { (ItemSortBy.SortName, SortOrder.Ascending) }
-                }).Select(i => GetChannelFeatures(i.ToString("N", CultureInfo.InvariantCulture))).ToArray();
+                }).Select(i => GetChannelFeatures(i)).ToArray();
         }
 
         /// <inheritdoc />
-        public ChannelFeatures GetChannelFeatures(string id)
+        public ChannelFeatures GetChannelFeatures(Guid? id)
         {
-            if (string.IsNullOrEmpty(id))
+            if (!id.HasValue)
             {
                 throw new ArgumentNullException(nameof(id));
             }
 
-            var channel = GetChannel(id);
+            var channel = GetChannel(id.Value);
             var channelProvider = GetChannelProvider(channel);
 
             return GetChannelFeaturesDto(channel, channelProvider, channelProvider.GetChannelFeatures());
diff --git a/Emby.Server.Implementations/Library/LibraryManager.cs b/Emby.Server.Implementations/Library/LibraryManager.cs
index 013781258e..5b926b0f4f 100644
--- a/Emby.Server.Implementations/Library/LibraryManager.cs
+++ b/Emby.Server.Implementations/Library/LibraryManager.cs
@@ -2462,9 +2462,19 @@ namespace Emby.Server.Implementations.Library
 
         public BaseItem GetParentItem(string parentId, Guid? userId)
         {
-            if (!string.IsNullOrEmpty(parentId))
+            if (string.IsNullOrEmpty(parentId))
             {
-                return GetItemById(new Guid(parentId));
+                return GetParentItem((Guid?)null, userId);
+            }
+
+            return GetParentItem(new Guid(parentId), userId);
+        }
+
+        public BaseItem GetParentItem(Guid? parentId, Guid? userId)
+        {
+            if (parentId.HasValue)
+            {
+                return GetItemById(parentId.Value);
             }
 
             if (userId.HasValue && userId != Guid.Empty)
diff --git a/Emby.Server.Implementations/Library/SearchEngine.cs b/Emby.Server.Implementations/Library/SearchEngine.cs
index c850e3a082..1d9529dff4 100644
--- a/Emby.Server.Implementations/Library/SearchEngine.cs
+++ b/Emby.Server.Implementations/Library/SearchEngine.cs
@@ -156,8 +156,8 @@ namespace Emby.Server.Implementations.Library
                 ExcludeItemTypes = excludeItemTypes.ToArray(),
                 IncludeItemTypes = includeItemTypes.ToArray(),
                 Limit = query.Limit,
-                IncludeItemsByName = string.IsNullOrEmpty(query.ParentId),
-                ParentId = string.IsNullOrEmpty(query.ParentId) ? Guid.Empty : new Guid(query.ParentId),
+                IncludeItemsByName = !query.ParentId.HasValue,
+                ParentId = query.ParentId ?? Guid.Empty,
                 OrderBy = new[] { (ItemSortBy.SortName, SortOrder.Ascending) },
                 Recursive = true,
 
diff --git a/Emby.Server.Implementations/TV/TVSeriesManager.cs b/Emby.Server.Implementations/TV/TVSeriesManager.cs
index 3cfcecbd1e..447c587f99 100644
--- a/Emby.Server.Implementations/TV/TVSeriesManager.cs
+++ b/Emby.Server.Implementations/TV/TVSeriesManager.cs
@@ -56,13 +56,11 @@ namespace Emby.Server.Implementations.TV
                 return GetResult(GetNextUpEpisodes(request, user, new[] { presentationUniqueKey }, dtoOptions), request);
             }
 
-            var parentIdGuid = string.IsNullOrEmpty(request.ParentId) ? (Guid?)null : new Guid(request.ParentId);
-
             BaseItem[] parents;
 
-            if (parentIdGuid.HasValue)
+            if (request.ParentId.HasValue)
             {
-                var parent = _libraryManager.GetItemById(parentIdGuid.Value);
+                var parent = _libraryManager.GetItemById(request.ParentId.Value);
 
                 if (parent != null)
                 {
diff --git a/Jellyfin.Api/Controllers/ArtistsController.cs b/Jellyfin.Api/Controllers/ArtistsController.cs
index c65dc86201..fed7ed3e5a 100644
--- a/Jellyfin.Api/Controllers/ArtistsController.cs
+++ b/Jellyfin.Api/Controllers/ArtistsController.cs
@@ -3,7 +3,6 @@ using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using Jellyfin.Api.Constants;
 using Jellyfin.Api.Extensions;
-using Jellyfin.Api.Helpers;
 using Jellyfin.Api.ModelBinders;
 using Jellyfin.Data.Entities;
 using MediaBrowser.Controller.Dto;
@@ -87,7 +86,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -119,16 +118,11 @@ namespace Jellyfin.Api.Controllers
                 .AddAdditionalDtoOptions(enableImages, enableUserData, imageTypeLimit, enableImageTypes);
 
             User? user = null;
-            BaseItem parentItem;
+            BaseItem parentItem = _libraryManager.GetParentItem(parentId, userId);
 
             if (userId.HasValue && !userId.Equals(Guid.Empty))
             {
                 user = _userManager.GetUserById(userId.Value);
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.GetUserRootFolder() : _libraryManager.GetItemById(parentId);
-            }
-            else
-            {
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.RootFolder : _libraryManager.GetItemById(parentId);
             }
 
             var query = new InternalItemsQuery(user)
@@ -157,15 +151,15 @@ namespace Jellyfin.Api.Controllers
                 EnableTotalRecordCount = enableTotalRecordCount
             };
 
-            if (!string.IsNullOrWhiteSpace(parentId))
+            if (parentId.HasValue)
             {
                 if (parentItem is Folder)
                 {
-                    query.AncestorIds = new[] { new Guid(parentId) };
+                    query.AncestorIds = new[] { parentId.Value };
                 }
                 else
                 {
-                    query.ItemIds = new[] { new Guid(parentId) };
+                    query.ItemIds = new[] { parentId.Value };
                 }
             }
 
@@ -291,7 +285,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -323,16 +317,11 @@ namespace Jellyfin.Api.Controllers
                 .AddAdditionalDtoOptions(enableImages, enableUserData, imageTypeLimit, enableImageTypes);
 
             User? user = null;
-            BaseItem parentItem;
+            BaseItem parentItem = _libraryManager.GetParentItem(parentId, userId);
 
             if (userId.HasValue && !userId.Equals(Guid.Empty))
             {
                 user = _userManager.GetUserById(userId.Value);
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.GetUserRootFolder() : _libraryManager.GetItemById(parentId);
-            }
-            else
-            {
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.RootFolder : _libraryManager.GetItemById(parentId);
             }
 
             var query = new InternalItemsQuery(user)
@@ -361,15 +350,15 @@ namespace Jellyfin.Api.Controllers
                 EnableTotalRecordCount = enableTotalRecordCount
             };
 
-            if (!string.IsNullOrWhiteSpace(parentId))
+            if (parentId.HasValue)
             {
                 if (parentItem is Folder)
                 {
-                    query.AncestorIds = new[] { new Guid(parentId) };
+                    query.AncestorIds = new[] { parentId.Value };
                 }
                 else
                 {
-                    query.ItemIds = new[] { new Guid(parentId) };
+                    query.ItemIds = new[] { parentId.Value };
                 }
             }
 
diff --git a/Jellyfin.Api/Controllers/ChannelsController.cs b/Jellyfin.Api/Controllers/ChannelsController.cs
index c4dc44cc36..b70c76e807 100644
--- a/Jellyfin.Api/Controllers/ChannelsController.cs
+++ b/Jellyfin.Api/Controllers/ChannelsController.cs
@@ -92,7 +92,7 @@ namespace Jellyfin.Api.Controllers
         /// <response code="200">Channel features returned.</response>
         /// <returns>An <see cref="OkResult"/> containing the channel features.</returns>
         [HttpGet("{channelId}/Features")]
-        public ActionResult<ChannelFeatures> GetChannelFeatures([FromRoute, Required] string channelId)
+        public ActionResult<ChannelFeatures> GetChannelFeatures([FromRoute, Required] Guid channelId)
         {
             return _channelManager.GetChannelFeatures(channelId);
         }
diff --git a/Jellyfin.Api/Controllers/FilterController.cs b/Jellyfin.Api/Controllers/FilterController.cs
index 31cb9e2736..1c0f1c1dfe 100644
--- a/Jellyfin.Api/Controllers/FilterController.cs
+++ b/Jellyfin.Api/Controllers/FilterController.cs
@@ -50,33 +50,24 @@ namespace Jellyfin.Api.Controllers
         [ProducesResponseType(StatusCodes.Status200OK)]
         public ActionResult<QueryFiltersLegacy> GetQueryFiltersLegacy(
             [FromQuery] Guid? userId,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] mediaTypes)
         {
-            var parentItem = string.IsNullOrEmpty(parentId)
-                ? null
-                : _libraryManager.GetItemById(parentId);
-
             var user = userId.HasValue && !userId.Equals(Guid.Empty)
                 ? _userManager.GetUserById(userId.Value)
                 : null;
 
-            if (includeItemTypes.Length == 1
-                && (string.Equals(includeItemTypes[0], nameof(BoxSet), StringComparison.OrdinalIgnoreCase)
-                    || string.Equals(includeItemTypes[0], nameof(Playlist), StringComparison.OrdinalIgnoreCase)
-                    || string.Equals(includeItemTypes[0], nameof(Trailer), StringComparison.OrdinalIgnoreCase)
-                    || string.Equals(includeItemTypes[0], "Program", StringComparison.OrdinalIgnoreCase)))
+            BaseItem? item = null;
+            if (includeItemTypes.Length != 1
+                || !(string.Equals(includeItemTypes[0], nameof(BoxSet), StringComparison.OrdinalIgnoreCase)
+                     || string.Equals(includeItemTypes[0], nameof(Playlist), StringComparison.OrdinalIgnoreCase)
+                     || string.Equals(includeItemTypes[0], nameof(Trailer), StringComparison.OrdinalIgnoreCase)
+                     || string.Equals(includeItemTypes[0], "Program", StringComparison.OrdinalIgnoreCase)))
             {
-                parentItem = null;
+                item = _libraryManager.GetParentItem(parentId, user?.Id);
             }
 
-            var item = string.IsNullOrEmpty(parentId)
-                ? user == null
-                    ? _libraryManager.RootFolder
-                    : _libraryManager.GetUserRootFolder()
-                : parentItem;
-
             var query = new InternalItemsQuery
             {
                 User = user,
@@ -140,7 +131,7 @@ namespace Jellyfin.Api.Controllers
         [ProducesResponseType(StatusCodes.Status200OK)]
         public ActionResult<QueryFilters> GetQueryFilters(
             [FromQuery] Guid? userId,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
             [FromQuery] bool? isAiring,
             [FromQuery] bool? isMovie,
@@ -150,14 +141,11 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] bool? isSeries,
             [FromQuery] bool? recursive)
         {
-            var parentItem = string.IsNullOrEmpty(parentId)
-                ? null
-                : _libraryManager.GetItemById(parentId);
-
             var user = userId.HasValue && !userId.Equals(Guid.Empty)
                 ? _userManager.GetUserById(userId.Value)
                 : null;
 
+            BaseItem? parentItem = null;
             if (includeItemTypes.Length == 1
                 && (string.Equals(includeItemTypes[0], nameof(BoxSet), StringComparison.OrdinalIgnoreCase)
                     || string.Equals(includeItemTypes[0], nameof(Playlist), StringComparison.OrdinalIgnoreCase)
@@ -166,6 +154,10 @@ namespace Jellyfin.Api.Controllers
             {
                 parentItem = null;
             }
+            else if (parentId.HasValue)
+            {
+                parentItem = _libraryManager.GetItemById(parentId.Value);
+            }
 
             var filters = new QueryFilters();
             var genreQuery = new InternalItemsQuery(user)
diff --git a/Jellyfin.Api/Controllers/GenresController.cs b/Jellyfin.Api/Controllers/GenresController.cs
index d2b41e0a8d..b6755ed5e5 100644
--- a/Jellyfin.Api/Controllers/GenresController.cs
+++ b/Jellyfin.Api/Controllers/GenresController.cs
@@ -72,7 +72,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -109,15 +109,15 @@ namespace Jellyfin.Api.Controllers
                 EnableTotalRecordCount = enableTotalRecordCount
             };
 
-            if (!string.IsNullOrWhiteSpace(parentId))
+            if (parentId.HasValue)
             {
                 if (parentItem is Folder)
                 {
-                    query.AncestorIds = new[] { new Guid(parentId) };
+                    query.AncestorIds = new[] { parentId.Value };
                 }
                 else
                 {
-                    query.ItemIds = new[] { new Guid(parentId) };
+                    query.ItemIds = new[] { parentId.Value };
                 }
             }
 
diff --git a/Jellyfin.Api/Controllers/ItemsController.cs b/Jellyfin.Api/Controllers/ItemsController.cs
index b0979fbcf7..7e9035f80f 100644
--- a/Jellyfin.Api/Controllers/ItemsController.cs
+++ b/Jellyfin.Api/Controllers/ItemsController.cs
@@ -176,7 +176,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] bool? recursive,
             [FromQuery] string? searchTerm,
             [FromQuery] string? sortOrder,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -239,14 +239,8 @@ namespace Jellyfin.Api.Controllers
                 parentId = null;
             }
 
-            BaseItem? item = null;
+            var item = _libraryManager.GetParentItem(parentId, userId);
             QueryResult<BaseItem> result;
-            if (!string.IsNullOrEmpty(parentId))
-            {
-                item = _libraryManager.GetItemById(parentId);
-            }
-
-            item ??= _libraryManager.GetUserRootFolder();
 
             if (!(item is Folder folder))
             {
@@ -343,7 +337,7 @@ namespace Jellyfin.Api.Controllers
                     ItemIds = ids,
                     MinCommunityRating = minCommunityRating,
                     MinCriticRating = minCriticRating,
-                    ParentId = string.IsNullOrWhiteSpace(parentId) ? Guid.Empty : new Guid(parentId),
+                    ParentId = parentId ?? Guid.Empty,
                     ParentIndexNumber = parentIndexNumber,
                     EnableTotalRecordCount = enableTotalRecordCount,
                     ExcludeItemIds = excludeItemIds,
@@ -615,7 +609,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] bool? recursive,
             [FromQuery] string? searchTerm,
             [FromQuery] string? sortOrder,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -773,7 +767,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] mediaTypes,
             [FromQuery] bool? enableUserData,
@@ -785,7 +779,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] bool? enableImages = true)
         {
             var user = _userManager.GetUserById(userId);
-            var parentIdGuid = string.IsNullOrWhiteSpace(parentId) ? Guid.Empty : new Guid(parentId);
+            var parentIdGuid = parentId ?? Guid.Empty;
             var dtoOptions = new DtoOptions { Fields = fields }
                 .AddClientFields(Request)
                 .AddAdditionalDtoOptions(enableImages, enableUserData, imageTypeLimit, enableImageTypes);
diff --git a/Jellyfin.Api/Controllers/LibraryController.cs b/Jellyfin.Api/Controllers/LibraryController.cs
index 3ff77e8e01..184843b397 100644
--- a/Jellyfin.Api/Controllers/LibraryController.cs
+++ b/Jellyfin.Api/Controllers/LibraryController.cs
@@ -362,7 +362,7 @@ namespace Jellyfin.Api.Controllers
         [Authorize(Policy = Policies.DefaultAuthorization)]
         [ProducesResponseType(StatusCodes.Status204NoContent)]
         [ProducesResponseType(StatusCodes.Status401Unauthorized)]
-        public ActionResult DeleteItems([FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] ids)
+        public ActionResult DeleteItems([FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] Guid[] ids)
         {
             if (ids.Length == 0)
             {
diff --git a/Jellyfin.Api/Controllers/MoviesController.cs b/Jellyfin.Api/Controllers/MoviesController.cs
index 75dfd4e68b..4d788ad7d3 100644
--- a/Jellyfin.Api/Controllers/MoviesController.cs
+++ b/Jellyfin.Api/Controllers/MoviesController.cs
@@ -65,7 +65,7 @@ namespace Jellyfin.Api.Controllers
         [HttpGet("Recommendations")]
         public ActionResult<IEnumerable<RecommendationDto>> GetMovieRecommendations(
             [FromQuery] Guid? userId,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery] int categoryLimit = 5,
             [FromQuery] int itemLimit = 8)
@@ -78,7 +78,7 @@ namespace Jellyfin.Api.Controllers
 
             var categories = new List<RecommendationDto>();
 
-            var parentIdGuid = string.IsNullOrWhiteSpace(parentId) ? Guid.Empty : new Guid(parentId);
+            var parentIdGuid = parentId ?? Guid.Empty;
 
             var query = new InternalItemsQuery(user)
             {
diff --git a/Jellyfin.Api/Controllers/MusicGenresController.cs b/Jellyfin.Api/Controllers/MusicGenresController.cs
index e7d0a61c58..2608a9cd09 100644
--- a/Jellyfin.Api/Controllers/MusicGenresController.cs
+++ b/Jellyfin.Api/Controllers/MusicGenresController.cs
@@ -72,7 +72,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -109,15 +109,15 @@ namespace Jellyfin.Api.Controllers
                 EnableTotalRecordCount = enableTotalRecordCount
             };
 
-            if (!string.IsNullOrWhiteSpace(parentId))
+            if (parentId.HasValue)
             {
                 if (parentItem is Folder)
                 {
-                    query.AncestorIds = new[] { new Guid(parentId) };
+                    query.AncestorIds = new[] { parentId.Value };
                 }
                 else
                 {
-                    query.ItemIds = new[] { new Guid(parentId) };
+                    query.ItemIds = new[] { parentId.Value };
                 }
             }
 
diff --git a/Jellyfin.Api/Controllers/PackageController.cs b/Jellyfin.Api/Controllers/PackageController.cs
index 83b3597665..6295dfc05d 100644
--- a/Jellyfin.Api/Controllers/PackageController.cs
+++ b/Jellyfin.Api/Controllers/PackageController.cs
@@ -45,13 +45,13 @@ namespace Jellyfin.Api.Controllers
         [ProducesResponseType(StatusCodes.Status200OK)]
         public async Task<ActionResult<PackageInfo>> GetPackageInfo(
             [FromRoute, Required] string name,
-            [FromQuery] string? assemblyGuid)
+            [FromQuery] Guid? assemblyGuid)
         {
             var packages = await _installationManager.GetAvailablePackages().ConfigureAwait(false);
             var result = _installationManager.FilterPackages(
                     packages,
                     name,
-                    string.IsNullOrEmpty(assemblyGuid) ? default : Guid.Parse(assemblyGuid))
+                    assemblyGuid ?? default)
                 .FirstOrDefault();
 
             if (result == null)
@@ -92,7 +92,7 @@ namespace Jellyfin.Api.Controllers
         [Authorize(Policy = Policies.RequiresElevation)]
         public async Task<ActionResult> InstallPackage(
             [FromRoute, Required] string name,
-            [FromQuery] string? assemblyGuid,
+            [FromQuery] Guid? assemblyGuid,
             [FromQuery] string? version,
             [FromQuery] string? repositoryUrl)
         {
@@ -106,7 +106,7 @@ namespace Jellyfin.Api.Controllers
             var package = _installationManager.GetCompatibleVersions(
                     packages,
                     name,
-                    string.IsNullOrEmpty(assemblyGuid) ? Guid.Empty : Guid.Parse(assemblyGuid),
+                    assemblyGuid ?? Guid.Empty,
                     specificVersion: string.IsNullOrEmpty(version) ? null : Version.Parse(version))
                 .FirstOrDefault();
 
diff --git a/Jellyfin.Api/Controllers/PersonsController.cs b/Jellyfin.Api/Controllers/PersonsController.cs
index aaad36551c..17e631197c 100644
--- a/Jellyfin.Api/Controllers/PersonsController.cs
+++ b/Jellyfin.Api/Controllers/PersonsController.cs
@@ -79,7 +79,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ImageType[] enableImageTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludePersonTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] personTypes,
-            [FromQuery] string? appearsInItemId,
+            [FromQuery] Guid? appearsInItemId,
             [FromQuery] Guid? userId,
             [FromQuery] bool? enableImages = true)
         {
@@ -102,7 +102,7 @@ namespace Jellyfin.Api.Controllers
                 NameContains = searchTerm,
                 User = user,
                 IsFavorite = !isFavorite.HasValue && isFavoriteInFilters ? true : isFavorite,
-                AppearsInItemId = string.IsNullOrEmpty(appearsInItemId) ? Guid.Empty : Guid.Parse(appearsInItemId),
+                AppearsInItemId = appearsInItemId ?? Guid.Empty,
                 Limit = limit ?? 0
             });
 
diff --git a/Jellyfin.Api/Controllers/SearchController.cs b/Jellyfin.Api/Controllers/SearchController.cs
index 076fe58f11..08255ff8f6 100644
--- a/Jellyfin.Api/Controllers/SearchController.cs
+++ b/Jellyfin.Api/Controllers/SearchController.cs
@@ -86,7 +86,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] mediaTypes,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery] bool? isMovie,
             [FromQuery] bool? isSeries,
             [FromQuery] bool? isNews,
diff --git a/Jellyfin.Api/Controllers/StudiosController.cs b/Jellyfin.Api/Controllers/StudiosController.cs
index 5090bf1dee..bb54c59f69 100644
--- a/Jellyfin.Api/Controllers/StudiosController.cs
+++ b/Jellyfin.Api/Controllers/StudiosController.cs
@@ -71,7 +71,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? searchTerm,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -109,15 +109,15 @@ namespace Jellyfin.Api.Controllers
                 EnableTotalRecordCount = enableTotalRecordCount
             };
 
-            if (!string.IsNullOrWhiteSpace(parentId))
+            if (parentId.HasValue)
             {
                 if (parentItem is Folder)
                 {
-                    query.AncestorIds = new[] { new Guid(parentId) };
+                    query.AncestorIds = new[] { parentId.Value };
                 }
                 else
                 {
-                    query.ItemIds = new[] { new Guid(parentId) };
+                    query.ItemIds = new[] { parentId.Value };
                 }
             }
 
diff --git a/Jellyfin.Api/Controllers/TrailersController.cs b/Jellyfin.Api/Controllers/TrailersController.cs
index 5b71fed5a0..8e9ece14f8 100644
--- a/Jellyfin.Api/Controllers/TrailersController.cs
+++ b/Jellyfin.Api/Controllers/TrailersController.cs
@@ -145,7 +145,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] bool? recursive,
             [FromQuery] string? searchTerm,
             [FromQuery] string? sortOrder,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFilter[] filters,
diff --git a/Jellyfin.Api/Controllers/TvShowsController.cs b/Jellyfin.Api/Controllers/TvShowsController.cs
index 57b056f50b..03fd1846d7 100644
--- a/Jellyfin.Api/Controllers/TvShowsController.cs
+++ b/Jellyfin.Api/Controllers/TvShowsController.cs
@@ -76,7 +76,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? limit,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery] string? seriesId,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery] bool? enableImges,
             [FromQuery] int? imageTypeLimit,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ImageType[] enableImageTypes,
@@ -132,7 +132,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery] bool? enableImges,
             [FromQuery] int? imageTypeLimit,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ImageType[] enableImageTypes,
@@ -144,7 +144,7 @@ namespace Jellyfin.Api.Controllers
 
             var minPremiereDate = DateTime.Now.Date.ToUniversalTime().AddDays(-1);
 
-            var parentIdGuid = string.IsNullOrWhiteSpace(parentId) ? Guid.Empty : new Guid(parentId);
+            var parentIdGuid = parentId ?? Guid.Empty;
 
             var options = new DtoOptions { Fields = fields }
                 .AddClientFields(Request)
@@ -194,14 +194,14 @@ namespace Jellyfin.Api.Controllers
         [ProducesResponseType(StatusCodes.Status200OK)]
         [ProducesResponseType(StatusCodes.Status404NotFound)]
         public ActionResult<QueryResult<BaseItemDto>> GetEpisodes(
-            [FromRoute, Required] string seriesId,
+            [FromRoute, Required] Guid seriesId,
             [FromQuery] Guid? userId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery] int? season,
-            [FromQuery] string? seasonId,
+            [FromQuery] Guid? seasonId,
             [FromQuery] bool? isMissing,
             [FromQuery] string? adjacentTo,
-            [FromQuery] string? startItemId,
+            [FromQuery] Guid? startItemId,
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] bool? enableImages,
@@ -220,9 +220,9 @@ namespace Jellyfin.Api.Controllers
                 .AddClientFields(Request)
                 .AddAdditionalDtoOptions(enableImages, enableUserData, imageTypeLimit, enableImageTypes!);
 
-            if (!string.IsNullOrWhiteSpace(seasonId)) // Season id was supplied. Get episodes by season id.
+            if (seasonId.HasValue) // Season id was supplied. Get episodes by season id.
             {
-                var item = _libraryManager.GetItemById(new Guid(seasonId));
+                var item = _libraryManager.GetItemById(seasonId.Value);
                 if (!(item is Season seasonItem))
                 {
                     return NotFound("No season exists with Id " + seasonId);
@@ -264,10 +264,10 @@ namespace Jellyfin.Api.Controllers
                     .ToList();
             }
 
-            if (!string.IsNullOrWhiteSpace(startItemId))
+            if (startItemId.HasValue)
             {
                 episodes = episodes
-                    .SkipWhile(i => !string.Equals(i.Id.ToString("N", CultureInfo.InvariantCulture), startItemId, StringComparison.OrdinalIgnoreCase))
+                    .SkipWhile(i => startItemId.Value.Equals(i.Id))
                     .ToList();
             }
 
@@ -316,7 +316,7 @@ namespace Jellyfin.Api.Controllers
         [ProducesResponseType(StatusCodes.Status200OK)]
         [ProducesResponseType(StatusCodes.Status404NotFound)]
         public ActionResult<QueryResult<BaseItemDto>> GetSeasons(
-            [FromRoute, Required] string seriesId,
+            [FromRoute, Required] Guid seriesId,
             [FromQuery] Guid? userId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery] bool? isSpecialSeason,
diff --git a/Jellyfin.Api/Controllers/YearsController.cs b/Jellyfin.Api/Controllers/YearsController.cs
index ec7c3de97f..48c639b08d 100644
--- a/Jellyfin.Api/Controllers/YearsController.cs
+++ b/Jellyfin.Api/Controllers/YearsController.cs
@@ -71,7 +71,7 @@ namespace Jellyfin.Api.Controllers
             [FromQuery] int? startIndex,
             [FromQuery] int? limit,
             [FromQuery] string? sortOrder,
-            [FromQuery] string? parentId,
+            [FromQuery] Guid? parentId,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] ItemFields[] fields,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] excludeItemTypes,
             [FromQuery, ModelBinder(typeof(CommaDelimitedArrayModelBinder))] string[] includeItemTypes,
@@ -89,16 +89,11 @@ namespace Jellyfin.Api.Controllers
                 .AddAdditionalDtoOptions(enableImages, enableUserData, imageTypeLimit, enableImageTypes);
 
             User? user = null;
-            BaseItem parentItem;
+            BaseItem parentItem = _libraryManager.GetParentItem(parentId, userId);
 
             if (userId.HasValue && !userId.Equals(Guid.Empty))
             {
                 user = _userManager.GetUserById(userId.Value);
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.GetUserRootFolder() : _libraryManager.GetItemById(parentId);
-            }
-            else
-            {
-                parentItem = string.IsNullOrEmpty(parentId) ? _libraryManager.RootFolder : _libraryManager.GetItemById(parentId);
             }
 
             IList<BaseItem> items;
diff --git a/MediaBrowser.Controller/Channels/IChannelManager.cs b/MediaBrowser.Controller/Channels/IChannelManager.cs
index 9a9d22d33d..ddae7dbd3e 100644
--- a/MediaBrowser.Controller/Channels/IChannelManager.cs
+++ b/MediaBrowser.Controller/Channels/IChannelManager.cs
@@ -24,7 +24,7 @@ namespace MediaBrowser.Controller.Channels
         /// </summary>
         /// <param name="id">The identifier.</param>
         /// <returns>ChannelFeatures.</returns>
-        ChannelFeatures GetChannelFeatures(string id);
+        ChannelFeatures GetChannelFeatures(Guid? id);
 
         /// <summary>
         /// Gets all channel features.
diff --git a/MediaBrowser.Controller/Library/ILibraryManager.cs b/MediaBrowser.Controller/Library/ILibraryManager.cs
index 601ca35360..24b101694d 100644
--- a/MediaBrowser.Controller/Library/ILibraryManager.cs
+++ b/MediaBrowser.Controller/Library/ILibraryManager.cs
@@ -574,5 +574,7 @@ namespace MediaBrowser.Controller.Library
         void RunMetadataSavers(IReadOnlyList<BaseItem> items, ItemUpdateType updateReason);
 
         BaseItem GetParentItem(string parentId, Guid? userId);
+
+        BaseItem GetParentItem(Guid? parentId, Guid? userId);
     }
 }
diff --git a/MediaBrowser.Model/Querying/NextUpQuery.cs b/MediaBrowser.Model/Querying/NextUpQuery.cs
index ee13ffc168..4ad336d333 100644
--- a/MediaBrowser.Model/Querying/NextUpQuery.cs
+++ b/MediaBrowser.Model/Querying/NextUpQuery.cs
@@ -18,7 +18,7 @@ namespace MediaBrowser.Model.Querying
         /// Gets or sets the parent identifier.
         /// </summary>
         /// <value>The parent identifier.</value>
-        public string ParentId { get; set; }
+        public Guid? ParentId { get; set; }
 
         /// <summary>
         /// Gets or sets the series id.
diff --git a/MediaBrowser.Model/Search/SearchQuery.cs b/MediaBrowser.Model/Search/SearchQuery.cs
index 01ad319a43..ce60062cd3 100644
--- a/MediaBrowser.Model/Search/SearchQuery.cs
+++ b/MediaBrowser.Model/Search/SearchQuery.cs
@@ -47,7 +47,7 @@ namespace MediaBrowser.Model.Search
 
         public string[] ExcludeItemTypes { get; set; }
 
-        public string ParentId { get; set; }
+        public Guid? ParentId { get; set; }
 
         public bool? IsMovie { get; set; }