NetworkVariable<FixedStringXBytes> sync issue on Ownership change

[Fofanius]

Description

We faced problem with syncing FixedStringXBytes of the NetworkBehaviour when changing ownership of the corresponding NetworkObject

There are no probmlems with other supported type (float, bool, INetworkSerializable struct)

Reproduce Steps

1. Add next component to the project:

using Unity.Collections;
using Unity.Netcode;
using UnityEngine;

public class Sample : NetworkBehaviour
{
    [SerializeField] private NetworkVariable<FixedString64Bytes> _string1 = new NetworkVariable<FixedString64Bytes>(string.Empty);
    [SerializeField] private NetworkVariable<FixedString64Bytes> _string2 = new NetworkVariable<FixedString64Bytes>(string.Empty);

    public override void OnNetworkSpawn()
    {
        if(IsServer)
        {
            _string1.Value = "QWERTY";
            _string2.Value = "QWERTYASDFG";
        }
    }
}

2. Add this component to any NetworkObject on scene
3. Start Host/Server (optionaly connect with a few clients; clients count doesn't matter)
4. Change the ownership of the object (you can use server itself as an argument)
5. Observe OverflowException: Attempted to write without first calling TryBeginWrite() each frame

Actual Outcome

Error each frame on server side:

OverflowException: Attempted to write without first calling TryBeginWrite()
Unity.Netcode.FastBufferWriter.WriteByte (System.Byte value) (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Serialization/FastBufferWriter.cs:655)
Unity.Netcode.FixedStringSerializer`1[T].WriteDelta (Unity.Netcode.FastBufferWriter writer, T& value, T& previousValue) (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/NetworkVariable/NetworkVariableSerialization.cs:720)
Unity.Netcode.NetworkVariableSerialization`1[T].WriteDelta (Unity.Netcode.FastBufferWriter writer, T& value, T& previousValue) (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/NetworkVariable/NetworkVariableSerialization.cs:1642)
Unity.Netcode.NetworkVariable`1[T].WriteDelta (Unity.Netcode.FastBufferWriter writer) (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/NetworkVariable/NetworkVariable.cs:198)
Unity.Netcode.NetworkVariableDeltaMessage.Serialize (Unity.Netcode.FastBufferWriter writer, System.Int32 targetVersion) (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Messaging/Messages/NetworkVariableDeltaMessage.cs:111)
Unity.Netcode.NetworkBehaviour.NetworkVariableUpdate (System.UInt64 targetClientId, System.Int32 behaviourIndex) (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Core/NetworkBehaviour.cs:909)
Unity.Netcode.NetworkBehaviour.VariableUpdate (System.UInt64 targetClientId) (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Core/NetworkBehaviour.cs:860)
Unity.Netcode.NetworkBehaviourUpdater.NetworkBehaviourUpdate () (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Core/NetworkBehaviourUpdater.cs:57)
Unity.Netcode.NetworkBehaviourUpdater.NetworkBehaviourUpdater_Tick () (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Core/NetworkBehaviourUpdater.cs:129)
Unity.Netcode.NetworkTickSystem.UpdateTick (System.Double localTimeSec, System.Double serverTimeSec) (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Timing/NetworkTickSystem.cs:102)
Unity.Netcode.NetworkTimeSystem.UpdateTime () (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Timing/NetworkTimeSystem.cs:141)
Unity.Netcode.NetworkManager.NetworkUpdate (Unity.Netcode.NetworkUpdateStage updateStage) (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Core/NetworkManager.cs:57)
Unity.Netcode.NetworkUpdateLoop.RunNetworkUpdateStage (Unity.Netcode.NetworkUpdateStage updateStage) (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Core/NetworkUpdateLoop.cs:192)
Unity.Netcode.NetworkUpdateLoop+NetworkPreUpdate+<>c.<CreateLoopSystem>b__0_0 () (at ./Library/PackageCache/com.unity.netcode.gameobjects@1.9.1/Runtime/Core/NetworkUpdateLoop.cs:239)

Expected Outcome

Same behaviour as for other supported types

Environment

• OS: Windows 10
• Unity Version: 2023.2.18f1
• Netcode Version: 1.9.1

[NoelStephensUnity]

Hi @Fofanius,

I think this could have been resolved in #2953. Could you update your project's Packages\Manifest.json com.unity.netcode.gameobjects entry with the below modifications and let me know if you no longer experience this issue?

"com.unity.netcode.gameobjects": "https://github.com/Unity-Technologies/com.unity.netcode.gameobjects.git?path=com.unity.netcode.gameobjects#develop",