[Bug] .NET 10 String sourcePlayer passed in Natives broken

[unknown-urge]

Summary

[FromSource] string from playerConnecting cannot be used with native methods that expect a player source string.

I'm not sure if this has already been reported, but I noticed an inconsistency with the new .NET runtime.

In the playerConnecting event, the player source is exposed as:

[FromSource] string sourcePlayer

Several native methods (such as GetNumPlayerIdentifiers and GetPlayerIdentifierByType) also accept a string representing the player source, so I expected the value provided by [FromSource] to work directly with these methods.

For example:

[OnEvent("playerConnecting")]
public async Task OnPlayerConnecting(
    [FromSource] string sourcePlayer,
    string playerName,
    Action<string> setKickReason,
    IDictionary<string, FunctionReference> connectionDeferrals)
{
    Console.WriteLine(sourcePlayer);

    var count = Native.GetNumPlayerIdentifiers(sourcePlayer);
    Console.WriteLine(count);

    var discord = Native.GetPlayerIdentifierByType(sourcePlayer, "discord");

    connectionDeferrals["done"].CallVoid();
}

The sourcePlayer value is printed correctly, but passing it to native methods such as GetNumPlayerIdentifiers or GetPlayerIdentifierByType causes the server to throw an exception.

Expected behavior

The value received from [FromSource] string sourcePlayer should be directly usable with native methods that accept a player source as a string, such as:

Native.GetNumPlayerIdentifiers(sourcePlayer)
Native.GetPlayerIdentifierByType(sourcePlayer, "discord")

Actual behavior

Passing the value obtained from [FromSource] into these native methods throws an exception on the server.

This makes it unclear whether:

the value provided by [FromSource] is not the expected player source,
the native method signatures are incorrect,
or an internal conversion is missing.

If [FromSource] string is intended to represent the player's server ID, it should be accepted by these native methods without throwing.

Here is exact error:

[22-07-2026 17:43:33] [   error] [            abrp] Error handling connection for MoodyFrog5473: System.Runtime.InteropServices.SEHException (0x80004005): External component has thrown an exception.
   at CitizenFX.Base.NativeApi.Invoke(UInt64 hash, String nativeName)
   at CitizenFX.FiveM.Server.Native.GetNumPlayerIdentifiers(String client)
   at Project.ServerScript.OnPlayerConnecting(String sourcePlayer, String playerName, Action`1 setKickReason, IDictionary`2 connectionDeferrals)

Issue type

Server

Repro rate

Always

Server build version

FXServer-early-access b93 win32

OS

No response

CPU

No response

GPU

No response

RAM

No response

Storage type

None

Connection type

None

ISP and bandwidth

No response

DxDiag

No response

Network graph

No response

Platform

Windows

OS version / distribution

Windows 11

CPU

No response

RAM

No response

Using txAdmin?

Yes

Hosting provider

None

Machine type

None

/perf endpoint output

No response

DDoS protection

No response

ulimit -n value (Linux only)

No response

Docker Compose file (Docker only)

No response

Steps to Reproduce

[OnEvent("playerConnecting")]
public async Task OnPlayerConnecting(
    [FromSource] string sourcePlayer,
    string playerName,
    Action<string> setKickReason,
    IDictionary<string, FunctionReference> connectionDeferrals)
{
    Console.WriteLine(sourcePlayer);

    var count = Native.GetNumPlayerIdentifiers(sourcePlayer);
    Console.WriteLine(count);

    var discord = Native.GetPlayerIdentifierByType(sourcePlayer, "discord");

    connectionDeferrals["done"].CallVoid();
}

Expected Behavior

No exception should be thrown.

Actual Behavior

Exception thrown.

Evidence

[22-07-2026 17:43:33] [   error] [            abrp] Error handling connection for MoodyFrog5473: System.Runtime.InteropServices.SEHException (0x80004005): External component has thrown an exception.
   at CitizenFX.Base.NativeApi.Invoke(UInt64 hash, String nativeName)
   at CitizenFX.FiveM.Server.Native.GetNumPlayerIdentifiers(String client)
   at Project.ServerScript.OnPlayerConnecting(String sourcePlayer, String playerName, Action`1 setKickReason, IDictionary`2 connectionDeferrals)

Additional Context

No response

[unknown-urge]

Workaround: The value returned by [FromSource] string sourcePlayer is in the format internal-net: (e.g. internal-net:1). Native functions such as GetNumPlayerIdentifiers and GetPlayerIdentifierByType expect only the numeric player source (e.g. 1). Stripping everything before the : allows these natives to work correctly. Ideally, [FromSource] should either return the native player source directly or the native APIs should accept the internal-net: format consistently.

Here is some code example:

[OnEvent("playerConnecting")]
public async Task OnPlayerConnecting(
    [FromSource] string sourcePlayer,
    string playerName,
    Action<string> setKickReason,
    IDictionary<string, FunctionReference> connectionDeferrals)
{
    try
    {
        // Workaround:
        // [FromSource] returns values such as "internal-net:1" instead of the
        // native player source ("1"). Native functions like
        // GetNumPlayerIdentifiers/GetPlayerIdentifierByType expect only the
        // numeric source ID, so strip the "internal-net:" prefix first.
        var separatorIndex = sourcePlayer.IndexOf(':');
        var nativeSource = separatorIndex >= 0
            ? sourcePlayer[(separatorIndex + 1)..]
            : sourcePlayer;

        API.Log.Info($"{playerName} ({sourcePlayer}) connecting");

        Console.WriteLine($"Managed source: {sourcePlayer}");
        Console.WriteLine($"Native source: {nativeSource}");

        var identifierCount = Native.GetNumPlayerIdentifiers(nativeSource);
        Console.WriteLine($"Identifier count: {identifierCount}");

        var discordIdentifier = Native.GetPlayerIdentifierByType(nativeSource, "discord");
        Console.WriteLine($"Discord identifier: {discordIdentifier}");

        connectionDeferrals["update"].CallVoid($"Welcome, {playerName}!");
        await API.Delay(500);

        connectionDeferrals["done"].CallVoid();
    }
    catch (Exception ex)
    {
        API.Log.Error($"Error handling connection for {playerName}: {ex}");
        connectionDeferrals["done"].CallVoid("An internal error occurred while processing your connection.");
    }
}

[europium-cfx]

Hey! Sorry for a rather late response on this.

[FromSource] attribute injects source depending on the argument type. If you request string, we inject full prefixed source string (consistently with how it worked in Legacy C# module). However, you can instead request a Player type (however this doesn't work properly in playerConnecting event handler specifically - that is tracked in #68) or int - that will be unprefixed numerical source value, just like in JS or Lua runtimes. You could even request any other type that can be casted to from int, that should work just fine, but I don't know if there are any real use cases to that.

[europium-cfx]

Additionally: GetNumPlayerIdentifiers and similar natives requesting player source expect just numerical value without a prefix by design. However, error handling for those natives will be improved in the coming patches, you will be able to see the actual error message instead of a SEHException 😄

[unknown-urge]

Hey, thanks for the response. One thing I don't quite understand. So in the events like playerConnecting, at the moment we have 3 options:

• FromSource with Player (which is known issue, but in the future will work)
• FromSource with Int (which I guess returns just the number)
• FromSource with string (which returns the 'internal-net:1' I talked about)

However, when using Native.GetPlayerIdentifierByType or most of the other Natives on server-side, the argument it asks for is string, which is quite confusing. So like it doesn't quite make sense to ask for string when the FromSource returns the un-formatted string.

That being said, is it possible / would it be possible to make the methods either accept Player as parameter for client, either accept Int?

Because right now, we would have to do int.ToString() everytime we would want to use a native.

Thanks.

[dBozee]

@europium-cfx to help reduce friction on the above, would it be possible to make Player.StrHandle public? We already have it stored on the object anyway, and it would save use having to do Player.Handle.ToString() anywhere it expects one.

[Gogsi]

A fix for this bug has been implemented and is available in the latest patch b96/97. Please try again and let us know if the issue persists. Thanks for your help!

[unknown-urge]

I don't think it is fixed. Tested it yesterday with the latest nuget (0.0.2) and latest build and it still occured.

[unknown-urge]

Here is exactly the code I use:

[OnEvent("playerConnecting")]
    public void OnPlayerConnecting([FromSource] string sourcePlayer, string playerName, Action<string> setKickReason, IDictionary<string, FunctionReference> connectionDeferrals)
    {
        try 
        {
            connectionDeferrals["update"].CallVoid("Checking requirements...");
            
            var discordLicense = Native.GetPlayerIdentifierByType(sourcePlayer, "discord");
            var isDiscordLicenseValid = !string.IsNullOrEmpty(discordLicense);
            if (!isDiscordLicenseValid)
            {
                connectionDeferrals["done"].CallVoid("No Discord License found.");
                return;
            }
            
            connectionDeferrals["done"].CallVoid();
        } 
        catch (Exception caughtEx) 
        { 
            API.Log.Error("An error occurred during player connection: " + caughtEx.Message + caughtEx.StackTrace, caughtEx.InnerException);
        }
    }

@Gogsi @europium-cfx