Install DayZ modsSteam Workshop mods, -mod= and the .bikey keys

Published on August 4, 2026 · last updated on November 8, 2026

Upload the mod files to the server

Every DayZ mod is a folder in the form @ModName. You upload these folders into your server's root directory with the WebFTP file manager in the browser or with an SFTP client. Pay attention to the exact folder name, including the leading @.

Upload a mod completely before you activate it. With the many small files of a large mod, a transfer can break off unnoticed - the folder is there, but incomplete, and the server fails to start with an error that does not point to the real cause.

Activate mods with a startup parameter

Mods are activated through the startup parameter -mod=. You separate several mods with semicolons - the order (load order) matters, and libraries such as the Community Framework go first:

-mod=@CF;@DayZ-Expansion;@AnotherMod

Server-side mods (which need no client download) go under -servermod= instead. You can set both parameters conveniently in the startup configuration in the web interface.

Store the BattlEye keys (.bikey)

This is the step where most modded servers fail: every mod comes with one or more .bikey files in its keys subfolder. Copy them into the server's central keys directory.

When a player joins, BattlEye checks every signature against these keys. If a key is missing, the player is kicked with a signature mismatch as soon as they come into contact with the mod content. Also make sure that verifySignatures = 2; is set in serverDZ.cfg.

Community Framework & load order

Many popular mods - including DayZ Expansion and most trader systems - require the Community Framework (CF) as a shared base. It has to be installed and loaded as early as possible in the mod list. Check the requirements of every mod on its Workshop page: dependencies have to be installed as well and loaded in the correct order.

A rule of thumb for the order has proven itself: libraries first, then maps, then content, and finally everything that builds on the previous ones. A mod that extends another one always goes after the mod it extends. Within a group, on the other hand, the order rarely matters.

What players have to download

DayZ does not download mods automatically - unlike Terraria or Project Zomboid, for example. Every player has to subscribe to the same mods in the Steam Workshop beforehand and load them at startup. That is why modded servers need a short guide for their community.

The most convenient route is often said to be the DZSA Launcher: it reads the server's mod list, downloads missing mods and starts DayZ with the right combination. Where it fits - and why we recommend the route through Steam - is covered in join a modded server. For a public modded server, a simple way to get the mods is practically the prerequisite for anyone joining at all.

The difference from -servermod= is crucial here: what you enter there runs exclusively on the server and does not have to be downloaded by anyone. Everything players can see or touch - weapons, vehicles, buildings - must go under -mod=. Client content under -servermod= leads to errors that are hard to interpret, because the server starts cleanly.

After a DayZ update

Every major DayZ update temporarily breaks mods until their authors catch up. The pattern is always the same: the server no longer starts or kicks players when they join, even though everything ran for days before.

1. Make a backup before the update - backups are self-service with us via WebFTP or SFTP, see create backups.
2. After the update, update all mods and transfer the .bikey files again. The keys change too, and an old key in the keys folder is a common source of errors.
3. Check whether a mod has no update at all yet. In that case, temporarily take it out of the load list instead of starting on the off chance.

If the start still does not go cleanly, server will not start helps you narrow it down. The fastest way to the cause is almost always to deactivate all mods and add them back one by one.

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