diff --git a/Trakt/Api/TraktApi.cs b/Trakt/Api/TraktApi.cs
index 9edf478..8b60e4b 100644
--- a/Trakt/Api/TraktApi.cs
+++ b/Trakt/Api/TraktApi.cs
@@ -47,6 +47,7 @@ public class TraktApi
     private readonly IHttpClientFactory _httpClientFactory;
     private readonly IServerApplicationHost _appHost;
     private readonly IUserDataManager _userDataManager;
+    private readonly IUserManager _userManager;
     private readonly JsonSerializerOptions _jsonOptions = JsonDefaults.Options;
 
     /// <summary>
@@ -56,15 +57,18 @@ public class TraktApi
     /// <param name="httpClientFactory">The <see cref="IHttpClientFactory"/>.</param>
     /// <param name="appHost">The <see cref="IServerApplicationHost"/>.</param>
     /// <param name="userDataManager">The <see cref="IUserDataManager"/>.</param>
+    /// <param name="userManager">The <see cref="IUserManager"/>.</param>
     public TraktApi(
         ILogger<TraktApi> logger,
         IHttpClientFactory httpClientFactory,
         IServerApplicationHost appHost,
-        IUserDataManager userDataManager)
+        IUserDataManager userDataManager,
+        IUserManager userManager)
     {
         _httpClientFactory = httpClientFactory;
         _appHost = appHost;
         _userDataManager = userDataManager;
+        _userManager = userManager;
         _logger = logger;
     }
 
@@ -707,10 +711,17 @@ public class TraktApi
         ArgumentOutOfRangeException.ThrowIfZero(movies.Count);
         ArgumentNullException.ThrowIfNull(traktUser);
 
+        var user = _userManager.GetUserById(traktUser.LinkedMbUserId);
+        if (user is null)
+        {
+            _logger.LogWarning("User id ({UserId}) linked to Trakt does not exist", traktUser.LinkedMbUserId);
+            return null;
+        }
+
         var moviesPayload = movies.Select(m =>
         {
             var lastPlayedDate = seen
-                ? _userDataManager.GetUserData(traktUser.LinkedMbUserId, m).LastPlayedDate
+                ? _userDataManager.GetUserData(user, m).LastPlayedDate
                 : null;
 
             return new TraktMovieWatched
@@ -784,6 +795,13 @@ public class TraktApi
         CancellationToken cancellationToken,
         bool useProviderIds = true)
     {
+        var user = _userManager.GetUserById(traktUser.LinkedMbUserId);
+        if (user is null)
+        {
+            _logger.LogWarning("User id ({UserId}) linked to Trakt does not exist", traktUser.LinkedMbUserId);
+            return null;
+        }
+
         var data = new TraktSyncWatched
         {
             Episodes = new List<TraktEpisodeWatched>(),
@@ -793,7 +811,7 @@ public class TraktApi
         foreach (var episode in episodeChunk)
         {
             var lastPlayedDate = seen
-                ? _userDataManager.GetUserData(traktUser.LinkedMbUserId, episode)
+                ? _userDataManager.GetUserData(user, episode)
                     .LastPlayedDate
                 : null;
 
diff --git a/Trakt/Api/TraktController.cs b/Trakt/Api/TraktController.cs
index 9140732..767e0f5 100644
--- a/Trakt/Api/TraktController.cs
+++ b/Trakt/Api/TraktController.cs
@@ -37,15 +37,17 @@ public class TraktController : ControllerBase
     /// <param name="libraryManager">Instance of the <see cref="ILibraryManager"/> interface.</param>
     /// <param name="httpClientFactory">Instance of the <see cref="IHttpClientFactory"/> interface.</param>
     /// <param name="appHost">Instance of the <see cref="IServerApplicationHost"/> interface.</param>
+    /// <param name="userManager">Instance of the <see cref="IUserManager"/> interface.</param>
     public TraktController(
         IUserDataManager userDataManager,
         ILoggerFactory loggerFactory,
         IHttpClientFactory httpClientFactory,
         IServerApplicationHost appHost,
-        ILibraryManager libraryManager)
+        ILibraryManager libraryManager,
+        IUserManager userManager)
     {
         _logger = loggerFactory.CreateLogger<TraktController>();
-        _traktApi = new TraktApi(loggerFactory.CreateLogger<TraktApi>(), httpClientFactory, appHost, userDataManager);
+        _traktApi = new TraktApi(loggerFactory.CreateLogger<TraktApi>(), httpClientFactory, appHost, userDataManager, userManager);
         _libraryManager = libraryManager;
     }
 
diff --git a/Trakt/ScheduledTasks/SyncFromTraktTask.cs b/Trakt/ScheduledTasks/SyncFromTraktTask.cs
index 519290a..ba73feb 100644
--- a/Trakt/ScheduledTasks/SyncFromTraktTask.cs
+++ b/Trakt/ScheduledTasks/SyncFromTraktTask.cs
@@ -58,7 +58,7 @@ public class SyncFromTraktTask : IScheduledTask
         _userDataManager = userDataManager;
         _libraryManager = libraryManager;
         _logger = loggerFactory.CreateLogger<SyncFromTraktTask>();
-        _traktApi = new TraktApi(loggerFactory.CreateLogger<TraktApi>(), httpClientFactory, appHost, userDataManager);
+        _traktApi = new TraktApi(loggerFactory.CreateLogger<TraktApi>(), httpClientFactory, appHost, userDataManager, userManager);
     }
 
     /// <inheritdoc />
@@ -206,7 +206,7 @@ public class SyncFromTraktTask : IScheduledTask
                 cancellationToken.ThrowIfCancellationRequested();
                 var matchedWatchedMovie = Extensions.FindMatch(movie, traktWatchedMovies);
                 var matchedPausedMovie = Extensions.FindMatch(movie, traktPausedMovies);
-                var userData = _userDataManager.GetUserData(user.Id, movie);
+                var userData = _userDataManager.GetUserData(user, movie);
                 bool changed = false;
 
                 if (matchedWatchedMovie != null)
@@ -304,7 +304,7 @@ public class SyncFromTraktTask : IScheduledTask
                 if (changed)
                 {
                     _userDataManager.SaveUserData(
-                        user.Id,
+                        user,
                         movie,
                         userData,
                         UserDataSaveReason.Import,
@@ -321,7 +321,7 @@ public class SyncFromTraktTask : IScheduledTask
                 cancellationToken.ThrowIfCancellationRequested();
                 var matchedWatchedShow = Extensions.FindMatch(episode.Series, traktWatchedShows);
                 var matchedPausedEpisode = Extensions.FindMatch(episode, traktPausedEpisodes);
-                var userData = _userDataManager.GetUserData(user.Id, episode);
+                var userData = _userDataManager.GetUserData(user, episode);
                 bool changed = false;
                 bool episodeWatched = false;
 
@@ -455,7 +455,7 @@ public class SyncFromTraktTask : IScheduledTask
                 if (changed)
                 {
                     _userDataManager.SaveUserData(
-                        user.Id,
+                        user,
                         episode,
                         userData,
                         UserDataSaveReason.Import,
diff --git a/Trakt/ScheduledTasks/SyncLibraryTask.cs b/Trakt/ScheduledTasks/SyncLibraryTask.cs
index 073d8d4..5b8ce1a 100644
--- a/Trakt/ScheduledTasks/SyncLibraryTask.cs
+++ b/Trakt/ScheduledTasks/SyncLibraryTask.cs
@@ -60,7 +60,7 @@ public class SyncLibraryTask : IScheduledTask
         _userDataManager = userDataManager;
         _libraryManager = libraryManager;
         _logger = loggerFactory.CreateLogger<SyncLibraryTask>();
-        _traktApi = new TraktApi(loggerFactory.CreateLogger<TraktApi>(), httpClientFactory, appHost, userDataManager);
+        _traktApi = new TraktApi(loggerFactory.CreateLogger<TraktApi>(), httpClientFactory, appHost, userDataManager, userManager);
     }
 
     /// <inheritdoc />
@@ -199,7 +199,7 @@ public class SyncLibraryTask : IScheduledTask
                 foreach (var libraryMovie in movieItems)
                 {
                     cancellationToken.ThrowIfCancellationRequested();
-                    var userData = _userDataManager.GetUserData(user.Id, libraryMovie);
+                    var userData = _userDataManager.GetUserData(user, libraryMovie);
 
                     if (traktUser.SynchronizeCollections)
                     {
@@ -438,7 +438,7 @@ public class SyncLibraryTask : IScheduledTask
                 foreach (var episode in episodeItems)
                 {
                     cancellationToken.ThrowIfCancellationRequested();
-                    var userData = _userDataManager.GetUserData(user.Id, episode);
+                    var userData = _userDataManager.GetUserData(user, episode);
                     var isPlayedTraktTv = false;
                     var traktWatchedShow = Extensions.FindMatch(episode.Series, traktWatchedShows);
 
diff --git a/Trakt/ServerMediator.cs b/Trakt/ServerMediator.cs
index f84cdb5..52591f1 100644
--- a/Trakt/ServerMediator.cs
+++ b/Trakt/ServerMediator.cs
@@ -44,13 +44,15 @@ public class ServerMediator : IHostedService, IDisposable
     /// <param name="loggerFactory">The <see cref="ILoggerFactory"/>.</param>
     /// <param name="httpClientFactory">The <see cref="IHttpClientFactory"/>.</param>
     /// <param name="appHost">The <see cref="IServerApplicationHost"/>.</param>
+    /// <param name="userManager">The <see cref="IUserManager"/>.</param>
     public ServerMediator(
         ISessionManager sessionManager,
         IUserDataManager userDataManager,
         ILibraryManager libraryManager,
         ILoggerFactory loggerFactory,
         IHttpClientFactory httpClientFactory,
-        IServerApplicationHost appHost)
+        IServerApplicationHost appHost,
+        IUserManager userManager)
     {
         _sessionManager = sessionManager;
         _libraryManager = libraryManager;
@@ -59,7 +61,7 @@ public class ServerMediator : IHostedService, IDisposable
         _logger = loggerFactory.CreateLogger<ServerMediator>();
         _playbackState = new Dictionary<Guid, PlaybackState>();
 
-        _traktApi = new TraktApi(loggerFactory.CreateLogger<TraktApi>(), httpClientFactory, appHost, userDataManager);
+        _traktApi = new TraktApi(loggerFactory.CreateLogger<TraktApi>(), httpClientFactory, appHost, userDataManager, userManager);
         _libraryManagerEventsHelper = new LibraryManagerEventsHelper(loggerFactory.CreateLogger<LibraryManagerEventsHelper>(), _traktApi);
         _userDataManagerEventsHelper = new UserDataManagerEventsHelper(loggerFactory.CreateLogger<UserDataManagerEventsHelper>(), _traktApi);
     }