How to add mods to your Arma 3 server

Arma 3 takes Steam Workshop mods such as maps, weapons and script frameworks, Creator DLCs such as Prairie Fire (loaded as mod folders), server-side only mods, and mods you upload yourself.

Back up first. See How to back up and restore your Arma 3 world.

Add a mod

1. Choose how each mod gets onto the server. Option A, upload the mod yourself (the most reliable way). Upload the mod's folder, with all lowercase names (for example @mymod), to the server's main folder in Files. Put the mod's .bikey file in the keys folder. Then add the folder name to Additional Mods, written with a semicolon after it (for example @mymod;), and restart the server. Use no capital letters, no spaces, and no folder names starting with a number.
2. Option B, list Workshop mods and let the server try to fetch them. In Additional Mods, write each Workshop mod as @ followed by its Workshop ID, separated by semicolons (for example @123456789;@987654321;), then restart the server. The server tries to download them when it starts. Automatic Workshop download is not guaranteed on our servers, so after the restart open Files and check that each mod now has its @ folder in the main folder. If a folder is missing, use Option A for that mod.
3. Option C, use a preset exported from the Arma 3 Launcher. In the Launcher, load your mods and export the preset as HTML. Upload that file to the main folder of the server and enter its exact file name in Modlist File, then restart. This relies on the same automatic download as Option B, so check for the @ folders in Files in the same way. Mods in Additional Mods load in addition to the preset.
4. Mods only the server needs. List them in Server-Side Only Mods, each followed by a semicolon. Players do not need these when the server checks mod signatures (the verifySignatures line in server.cfg), because the server then only accepts players whose mods match the keys in its keys folder.
5. Mods players may use but do not have to. List them in Optional Client-Side Mods in @WorkshopID form. Players can join with or without them.
6. Creator DLC. Set Arma 3 Branch (CDLC, etc.) to creatordlc and add the DLC's folder name, such as vn;, to Additional Mods. The branch change applies at the next update on start, so keep Automatic Updates ON.
7. If mods seem not to load, especially after copying them from Windows, turn on Make Mod Files Lowercase for one start, then turn it off again.
8. Players must load the same mods as the server in their Launcher, except for mods you listed as server-side only or optional.
9. To remove a mod, take it out of the lists above and restart. A mission or saved profile that needs that mod may stop loading, so make a panel backup first and remove one mod at a time. Deleting an uploaded mod folder removes its files for good.

Where files go

Open Files and use these places:

• keys (signature .bikey files, one per mod author)
• @modname or @workshopID folders at the top level of Files (the mod files)
• mpmissions (mission files)
• your exported preset file (for example modlist.html) at the top level of Files

Check it worked

After the restart, open Files and make sure each mod you listed has its folder in the main folder, then join the server with the same mods loaded in your Launcher. See How to add mods, plugins and modpacks.

If the server stops after you add a mod, remove the newest mod or restore your backup. See How to fix a server that will not start.