C# setup

The C# plugin API is two NuGet packages. The rest of the API is on Making a plugin. The C# example is a complete project to copy.

Package	Used by
vMenu.Enhanced.ClientAPI	your client script
vMenu.Enhanced.ServerAPI	your server script

Pin both to the vMenu Enhanced version your server runs. They bring the CitizenFX assemblies with them, so you do not reference those yourself.

Project layout

Keep the two halves in separate output folders. Each package ships its own copy of CitizenFX.Base.dll and CitizenFX.FiveM.Shared.dll, and two files with the same name cannot share a folder.

MyPlugin/
    fxmanifest.lua
    client/     the client assembly and everything it depends on
    server/     the server assembly and everything it depends on

Every client side DLL has to be listed in files, because players download those rather than reading them off the server’s disk:

fx_version 'cerulean'
games { 'gta5' }

files {
    'client/CitizenFX.Base.dll',
    'client/CitizenFX.FiveM.Shared.dll',
    'client/CitizenFX.FiveM.Client.dll',
    'client/MessagePack.dll',
    'client/MessagePack.Annotations.dll',
    'client/Microsoft.NET.StringTools.dll',
    'client/vMenu.Enhanced.PluginContracts.dll',
    'client/vMenu.Enhanced.ClientAPI.dll',
}

client_script 'client/MyPlugin.Client.dll'
server_script 'server/MyPlugin.Server.dll'

Add a package reference, check for a new DLL in your client output, add a line for it. Miss one and players get an assembly load error the moment they open the menu. The server half needs no files entries.

Call at least one native in Initialize

An Initialize that calls no FiveM code fails to load. This looks like a FiveM Enhanced bug. A logging statement is enough to work around it.

Things specific to C#

Topic	Detail
Entry points	VMenuPlugin.Create on the client, VMenuServer.RegisterAsync on the server, both from an IScript’s Initialize.
Text	Text.Literal and Text.Key. A plain string converts to a literal by itself.
Gates	PluginGate.Permission and PluginGate.Setting, combined with & and |. A plain string converts to a permission gate.
Batches	using (plugin.BeginBatch()) { ... }
Inserting rows	using (menu.InsertAt(2)) { ... }
Positions	Counted from 0.
Opening menus	await menu.RequestOpenAsync(), or RequestOpenAsync(MenuPriority.Medium). See standalone menus.

Compiler warnings

The vMenu.Enhanced.ClientAPI package brings an analyzer that warns about the two ways a plugin can take the screen away from the player.

Id	When
VMENU001	RequestOpenAsync with MenuPriority.High, or a priority only known at runtime.
VMENU002	RequestOpenAsync with doNotClose set, or a value only known at runtime.

Silence one per call with #pragma warning disable VMENU001 once you have made sure the call is warranted.

On a regular (legacy) FiveM server

The same two packages also have a .NET Framework 4.6.2 build for the regular FiveM runtime. NuGet picks it when your project targets .NET Framework 4.6.2 or newer.

Topic	Detail
Entry points	Call VMenuPlugin.Create and VMenuServer.RegisterAsync from your BaseScript’s constructor, or from an onResourceStart event handler for your own resource. Never call them from a tick. You do not have to wait for vMenu to start first: the plugin API registers as soon as vMenu is there, and again whenever it restarts. See start order and reconnecting.
Script files	Your client and server scripts must be named *.net.dll.
files	List Newtonsoft.Json.dll, System.ValueTuple.dll, vMenu.Enhanced.Polyfills.dll, vMenu.Enhanced.PluginContracts.dll and vMenu.Enhanced.ClientAPI.dll. The CitizenFX assemblies come with FiveM.
Newtonsoft.Json	The package ships the build legacy vMenu always used, which works in the client sandbox. Do not add the Newtonsoft.Json NuGet package next to it.