diff --git a/GameServer/Controllers/Api/PlayerCountApiController.cs b/GameServer/Controllers/Api/PlayerCountApiController.cs
index cd98457..29b6ee8 100644
--- a/GameServer/Controllers/Api/PlayerCountApiController.cs
+++ b/GameServer/Controllers/Api/PlayerCountApiController.cs
@@ -21,6 +21,7 @@ public IActionResult GetSessionCount(bool? isMnr = null)
         {
             return Content($"{Session.GetSessions()
                 .Where(x =>
+                    x != null &&    // TODO: Why are session objects becoming null?
                     (isMnr != null ? x.IsMNR == isMnr : true) &&
                     x.Authenticated &&
                     x.LastPing.AddMinutes(1) > DateTime.Now)
diff --git a/GameServer/Implementation/Common/Session.cs b/GameServer/Implementation/Common/Session.cs
index 8bc8ff3..0e97e81 100644
--- a/GameServer/Implementation/Common/Session.cs
+++ b/GameServer/Implementation/Common/Session.cs
@@ -1,27 +1,40 @@
-using GameServer.Models;
-using GameServer.Models.PlayerData;
-using GameServer.Models.Response;
+using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
-using System;
-using GameServer.Utils;
+using System.IO;
 using System.Linq;
-using NPTicket;
-using Serilog;
+using GameServer.Models;
 using GameServer.Models.Config;
-using System.IO;
+using GameServer.Models.PlayerData;
+using GameServer.Models.Response;
+using GameServer.Utils;
+using Microsoft.EntityFrameworkCore.Metadata.Internal;
 using Newtonsoft.Json;
+using NPTicket;
 using NPTicket.Verification;
 using NPTicket.Verification.Keys;
+using Serilog;
 
 namespace GameServer.Implementation.Common
 {
     public class Session
     {
-        private static readonly Dictionary<Guid, SessionInfo> Sessions = [];
+        private static readonly ConcurrentDictionary<Guid, SessionInfo> Sessions = [];
 
         public static string Login(Database database, string ip, Platform platform, string ticket, string hmac, string console_id, Guid SessionID)
         {
             ClearSessions();
+
+            if (!Sessions.ContainsKey(SessionID))
+            {
+                var errorResp = new Response<EmptyResponse>
+                {
+                    status = new ResponseStatus { id = -130, message = "The player doesn't exist" },
+                    response = new EmptyResponse { }
+                };
+                return errorResp.Serialize();
+            }
+
             byte[] ticketData = Convert.FromBase64String(ticket.Trim('\n').Trim('\0'));
             List<string> whitelist = [];
             if (ServerConfig.Instance.Whitelist)
@@ -126,7 +139,7 @@ public static string Login(Database database, string ip, Platform platform, stri
                     Quota = 30,
                     CreatedAt = TimeUtils.Now,
                     UpdatedAt = TimeUtils.Now,
-                    PolicyAccepted = Sessions[SessionID].PolicyAccepted,
+                    PolicyAccepted = Sessions.ContainsKey(SessionID) ? Sessions[SessionID].PolicyAccepted : false,
                 };
                 if (IsPSN)
                     newUser.PSNID = NPTicket.UserId;
@@ -154,10 +167,10 @@ public static string Login(Database database, string ip, Platform platform, stri
                 return errorResp.Serialize();
             }
 
-            foreach (var Session in Sessions.Where(match => match.Value.Username == user.Username 
-                && match.Key != SessionID && match.Value.Platform == platform))
+            foreach (var Session in Sessions.Where(match => match.Value == null || (match.Value.Username == user.Username 
+                && match.Key != SessionID && match.Value.Platform == platform)))
             {
-                Sessions.Remove(Session.Key);
+                Sessions.Remove(Session.Key, out _);
                 ServerCommunication.NotifySessionDestroyed(Session.Key);
             }
 
@@ -236,7 +249,7 @@ public static string SetPresence(string presence, Guid SessionID)
         public static Presence GetPresence(string Username)
         {
             ClearSessions();
-            var Session = Sessions.FirstOrDefault(match => match.Value.Username == Username).Value;
+            var Session = Sessions.FirstOrDefault(match => match.Value != null && match.Value.Username == Username).Value;
             if (Session == null) 
             {
                 return Presence.OFFLINE;
@@ -270,7 +283,7 @@ public static string Ping(Guid SessionID)
 
         public static void StartSession(Guid SessionID) 
         {
-            Sessions.Add(SessionID, new SessionInfo
+            Sessions.TryAdd(SessionID, new SessionInfo
             {
                 LastPing = TimeUtils.Now,
                 Presence = Presence.OFFLINE
@@ -279,18 +292,11 @@ public static void StartSession(Guid SessionID)
 
         private static void ClearSessions()
         {
-            foreach (var Session in Sessions.Where(match => match.Value.Authenticated
-                && (TimeUtils.Now > match.Value.LastPing.AddMinutes(60) /*|| TimeUtils.Now > match.Value.ExpiryDate*/)))
-            {
-                Sessions.Remove(Session.Key);
-                ServerCommunication.NotifySessionDestroyed(Session.Key);
-            }
-
-            foreach (var Session in Sessions.Where(match => !match.Value.Authenticated
-                && TimeUtils.Now > match.Value.LastPing.AddHours(3)))
+            foreach (var Session in Sessions.Where(match => match.Value == null || (TimeUtils.Now > match.Value.LastPing.AddMinutes(60) /*|| TimeUtils.Now > match.Value.ExpiryDate*/)))
             {
-                Sessions.Remove(Session.Key);
-                ServerCommunication.NotifySessionDestroyed(Session.Key);
+                var sessionKey = Session.Key;
+                Sessions.Remove(sessionKey, out _);
+                ServerCommunication.NotifySessionDestroyed(sessionKey);
             }
         }
 
@@ -348,7 +354,7 @@ public static void DestroyAllSessions()
         {
             foreach (var sessionID in Sessions.Keys.ToList())
             {
-                Sessions.Remove(sessionID);
+                Sessions.Remove(sessionID, out _);
                 ServerCommunication.NotifySessionDestroyed(sessionID);
             }
         }
diff --git a/GameServer/Models/PlayerData/SessionInfo.cs b/GameServer/Models/PlayerData/SessionInfo.cs
index c041d11..28cfb1d 100644
--- a/GameServer/Models/PlayerData/SessionInfo.cs
+++ b/GameServer/Models/PlayerData/SessionInfo.cs
@@ -8,7 +8,7 @@ public class SessionInfo
     {
         public string Username => Authenticated ? Ticket.Username : "";
         public Presence Presence { get; set; } = Presence.OFFLINE;
-        public DateTime ExpiryDate => Ticket.ExpiryDate.DateTime;
+        public DateTime ExpiryDate => Authenticated ? Ticket.ExpiryDate.DateTime : TimeUtils.Now;
         public Ticket Ticket { get; set; }
         public bool Authenticated => Ticket != null;
         public bool PolicyAccepted {  get; set; } = false;