2 files changed, 6 insertions, 1 deletions
diff --git a/Emby.Server.Implementations/Library/LibraryManager.cs b/Emby.Server.Implementations/Library/LibraryManager.cs
index f684f4dca3..52569ed66a 100644
--- a/Emby.Server.Implementations/Library/LibraryManager.cs
+++ b/Emby.Server.Implementations/Library/LibraryManager.cs
@@ -2315,9 +2315,13 @@ namespace Emby.Server.Implementations.Library
         {
             var comparer = Comparers.FirstOrDefault(c => name == c.Type);
 
-            // If it requires a user, create a new one, and assign the user
             if (comparer is IUserBaseItemComparer)
             {
+                if (user is null)
+                {
+                    throw new ArgumentException($"Sort key '{name}' requires a user, but none was provided.");
+                }
+
                 var userComparer = (IUserBaseItemComparer)Activator.CreateInstance(comparer.GetType())!; // only null for Nullable<T> instances
 
                 userComparer.User = user;
diff --git a/Emby.Server.Implementations/Library/UserDataManager.cs b/Emby.Server.Implementations/Library/UserDataManager.cs
index f5c41e5670..0680046c11 100644
--- a/Emby.Server.Implementations/Library/UserDataManager.cs
+++ b/Emby.Server.Implementations/Library/UserDataManager.cs
@@ -352,6 +352,7 @@ namespace Emby.Server.Implementations.Library
         /// <inheritdoc />
         public UserItemData? GetUserData(User user, BaseItem item)
         {
+            ArgumentNullException.ThrowIfNull(user);
             var row = ResolveUserDataRow(item, item.UserData?.Where(e => e.UserId.Equals(user.Id)));
             return row is not null ? Map(row) : new UserItemData()
             {