diff --git a/com.unity.netcode.gameobjects/CHANGELOG.md b/com.unity.netcode.gameobjects/CHANGELOG.md
index 49bf56231a..1c61b218a9 100644
--- a/com.unity.netcode.gameobjects/CHANGELOG.md
+++ b/com.unity.netcode.gameobjects/CHANGELOG.md
@@ -22,6 +22,7 @@ Additional documentation and release notes are available at [Multiplayer Documen
 
 ### Fixed
 
+- NestedNetworkVariables initialized with no value no longer throw an error. (#3891)
 
 ### Security
 
diff --git a/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/CollectionSerializationUtility.cs b/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/CollectionSerializationUtility.cs
index e8c61ceea7..d9327f2441 100644
--- a/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/CollectionSerializationUtility.cs
+++ b/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/CollectionSerializationUtility.cs
@@ -281,7 +281,7 @@ public static List<T> GetChangedList()
             }
         }
 
-        public static void WriteHashSetDelta<T>(FastBufferWriter writer, ref HashSet<T> value, ref HashSet<T> previousValue) where T : IEquatable<T>
+        public static void WriteHashSetDelta<T>(FastBufferWriter writer, ref HashSet<T> value, ref HashSet<T> previousValue)
         {
             // HashSets can be null, so we have to handle that case.
             // We do that by marking this as a full serialization and using the existing null handling logic
@@ -337,7 +337,7 @@ public static void WriteHashSetDelta<T>(FastBufferWriter writer, ref HashSet<T>
             }
         }
 
-        public static void ReadHashSetDelta<T>(FastBufferReader reader, ref HashSet<T> value) where T : IEquatable<T>
+        public static void ReadHashSetDelta<T>(FastBufferReader reader, ref HashSet<T> value)
         {
             // 1 = full serialization, 0 = delta serialization
             reader.ReadByteSafe(out byte full);
diff --git a/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/TypedILPPInitializers.cs b/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/TypedILPPInitializers.cs
index 8a639258da..9fd42b2ae3 100644
--- a/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/TypedILPPInitializers.cs
+++ b/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/TypedILPPInitializers.cs
@@ -103,7 +103,7 @@ public static void InitializeSerializer_List<T>()
         /// Registeres a native hash set (this generic implementation works with all types)
         /// </summary>
         /// <typeparam name="T">The type of elements contained in the HashSet, must implement IEquatable</typeparam>
-        public static void InitializeSerializer_HashSet<T>() where T : IEquatable<T>
+        public static void InitializeSerializer_HashSet<T>()
         {
             NetworkVariableSerialization<HashSet<T>>.Serializer = new HashSetSerializer<T>();
         }
diff --git a/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/TypedSerializerImplementations.cs b/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/TypedSerializerImplementations.cs
index 49e7e5e7cf..e1242378dd 100644
--- a/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/TypedSerializerImplementations.cs
+++ b/com.unity.netcode.gameobjects/Runtime/NetworkVariable/Serialization/TypedSerializerImplementations.cs
@@ -335,6 +335,12 @@ void INetworkVariableSerializer<List<T>>.ReadWithAllocator(FastBufferReader read
 
         public void Duplicate(in List<T> value, ref List<T> duplicatedValue)
         {
+            if (value == null)
+            {
+                duplicatedValue = null;
+                return;
+            }
+
             if (duplicatedValue == null)
             {
                 duplicatedValue = new List<T>();
@@ -351,7 +357,7 @@ public void Duplicate(in List<T> value, ref List<T> duplicatedValue)
         }
     }
 
-    internal class HashSetSerializer<T> : INetworkVariableSerializer<HashSet<T>> where T : IEquatable<T>
+    internal class HashSetSerializer<T> : INetworkVariableSerializer<HashSet<T>>
     {
         public void Write(FastBufferWriter writer, ref HashSet<T> value)
         {
@@ -414,6 +420,12 @@ void INetworkVariableSerializer<HashSet<T>>.ReadWithAllocator(FastBufferReader r
 
         public void Duplicate(in HashSet<T> value, ref HashSet<T> duplicatedValue)
         {
+            if (value == null)
+            {
+                duplicatedValue = null;
+                return;
+            }
+
             if (duplicatedValue == null)
             {
                 duplicatedValue = new HashSet<T>();
@@ -496,6 +508,12 @@ void INetworkVariableSerializer<Dictionary<TKey, TVal>>.ReadWithAllocator(FastBu
 
         public void Duplicate(in Dictionary<TKey, TVal> value, ref Dictionary<TKey, TVal> duplicatedValue)
         {
+            if (value == null)
+            {
+                duplicatedValue = null;
+                return;
+            }
+
             if (duplicatedValue == null)
             {
                 duplicatedValue = new Dictionary<TKey, TVal>();
diff --git a/com.unity.netcode.gameobjects/Tests/Runtime/NetworkVariable/NetworkVariableCollectionsTests.cs b/com.unity.netcode.gameobjects/Tests/Runtime/NetworkVariable/NetworkVariableCollectionsTests.cs
index 0154e4d6de..69e8727f27 100644
--- a/com.unity.netcode.gameobjects/Tests/Runtime/NetworkVariable/NetworkVariableCollectionsTests.cs
+++ b/com.unity.netcode.gameobjects/Tests/Runtime/NetworkVariable/NetworkVariableCollectionsTests.cs
@@ -1221,6 +1221,9 @@ public static void ResetState()
 
         public NetworkVariable<HashSet<int>> ListCollectionServer = new NetworkVariable<HashSet<int>>(new HashSet<int>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Server);
         public NetworkVariable<HashSet<int>> ListCollectionOwner = new NetworkVariable<HashSet<int>>(new HashSet<int>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Owner);
+        public NetworkVariable<HashSet<int>> UninitializedHashSet;
+        public NetworkVariable<HashSet<HashSet<int>>> UninitializedNestedHashSet;
+
         // This tracks what has changed per instance which is used to compare to all other instances
         internal Dictionary<Targets, Dictionary<DeltaTypes, HashSet<int>>> NetworkVariableChanges = new Dictionary<Targets, Dictionary<DeltaTypes, HashSet<int>>>();
 
@@ -1470,6 +1473,8 @@ public static void ResetState()
 
         public NetworkVariable<Dictionary<int, Dictionary<int, SerializableObject>>> ListCollectionServer = new NetworkVariable<Dictionary<int, Dictionary<int, SerializableObject>>>(new Dictionary<int, Dictionary<int, SerializableObject>>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Server);
         public NetworkVariable<Dictionary<int, Dictionary<int, SerializableObject>>> ListCollectionOwner = new NetworkVariable<Dictionary<int, Dictionary<int, SerializableObject>>>(new Dictionary<int, Dictionary<int, SerializableObject>>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Owner);
+        public NetworkVariable<Dictionary<int, Dictionary<int, SerializableObject>>> UninitializedNestedDictionary;
+
         // This tracks what has changed per instance which is used to compare to all other instances
         internal Dictionary<Targets, Dictionary<DeltaTypes, Dictionary<int, Dictionary<int, SerializableObject>>>> NetworkVariableChanges = new Dictionary<Targets, Dictionary<DeltaTypes, Dictionary<int, Dictionary<int, SerializableObject>>>>();
 
@@ -1777,6 +1782,8 @@ public static void ResetState()
 
         public NetworkVariable<Dictionary<int, SerializableObject>> ListCollectionServer = new NetworkVariable<Dictionary<int, SerializableObject>>(new Dictionary<int, SerializableObject>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Server);
         public NetworkVariable<Dictionary<int, SerializableObject>> ListCollectionOwner = new NetworkVariable<Dictionary<int, SerializableObject>>(new Dictionary<int, SerializableObject>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Owner);
+        public NetworkVariable<Dictionary<int, SerializableObject>> UninitializedDictionary;
+
         // This tracks what has changed per instance which is used to compare to all other instances
         internal Dictionary<Targets, Dictionary<DeltaTypes, Dictionary<int, SerializableObject>>> NetworkVariableChanges = new Dictionary<Targets, Dictionary<DeltaTypes, Dictionary<int, SerializableObject>>>();
 
@@ -2144,6 +2151,8 @@ public static void ResetState()
 
         public NetworkVariable<List<List<SerializableObject>>> ListCollectionServer = new NetworkVariable<List<List<SerializableObject>>>(new List<List<SerializableObject>>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Server);
         public NetworkVariable<List<List<SerializableObject>>> ListCollectionOwner = new NetworkVariable<List<List<SerializableObject>>>(new List<List<SerializableObject>>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Owner);
+        public NetworkVariable<List<List<SerializableObject>>> UninitializedNestedList;
+
         // This tracks what has changed per instance which is used to compare to all other instances
         internal Dictionary<Targets, Dictionary<DeltaTypes, List<List<SerializableObject>>>> NetworkVariableChanges = new Dictionary<Targets, Dictionary<DeltaTypes, List<List<SerializableObject>>>>();
 
@@ -2443,6 +2452,8 @@ public static void ResetState()
 
         public NetworkVariable<List<SerializableObject>> ListCollectionServer = new NetworkVariable<List<SerializableObject>>(new List<SerializableObject>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Server);
         public NetworkVariable<List<SerializableObject>> ListCollectionOwner = new NetworkVariable<List<SerializableObject>>(new List<SerializableObject>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Owner);
+        public NetworkVariable<List<SerializableObject>> UninitializedList;
+
         // This tracks what has changed per instance which is used to compare to all other instances
         internal Dictionary<Targets, Dictionary<DeltaTypes, List<SerializableObject>>> NetworkVariableChanges = new Dictionary<Targets, Dictionary<DeltaTypes, List<SerializableObject>>>();
 
@@ -2708,6 +2719,8 @@ public static void ResetState()
 
         public NetworkVariable<List<List<int>>> ListCollectionServer = new NetworkVariable<List<List<int>>>(new List<List<int>>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Server);
         public NetworkVariable<List<List<int>>> ListCollectionOwner = new NetworkVariable<List<List<int>>>(new List<List<int>>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Owner);
+        public NetworkVariable<List<List<int>>> UninitializedList;
+
         // This tracks what has changed per instance which is used to compare to all other instances
         internal Dictionary<Targets, Dictionary<DeltaTypes, List<List<int>>>> NetworkVariableChanges = new Dictionary<Targets, Dictionary<DeltaTypes, List<List<int>>>>();
 
@@ -3012,6 +3025,8 @@ public static void ResetState()
 
         public NetworkVariable<List<int>> ListCollectionServer = new NetworkVariable<List<int>>(new List<int>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Server);
         public NetworkVariable<List<int>> ListCollectionOwner = new NetworkVariable<List<int>>(new List<int>(), NetworkVariableReadPermission.Everyone, NetworkVariableWritePermission.Owner);
+        public NetworkVariable<List<int>> UninitializedList;
+
         // This tracks what has changed per instance which is used to compare to all other instances
         internal Dictionary<Targets, Dictionary<DeltaTypes, List<int>>> NetworkVariableChanges = new Dictionary<Targets, Dictionary<DeltaTypes, List<int>>>();