How to Install Mods on an Arma Reforger Server (config.json)

To install mods on an Arma Reforger server, find each mod on the Reforger Workshop, copy its 16 character mod ID, and add it to the mods array inside the game section of the server's config.json as { "modId": "...", "name": "..." }. Restart, and the server downloads the mods itself. Players get the same mods automatically when they join. Add a version only if you need to pin one.

Where do Arma Reforger mods come from?

Reforger has its own Workshop, run by Bohemia, separate from Steam. You can browse it in game from Workshop on the main menu, or on the web at the Arma Reforger Workshop. Each mod page shows:

The mod ID: a 16 character hexadecimal GUID, for example 1234567890ABCDEF (a placeholder, not a real mod). This is what the server needs.
The version: such as 1.2.3.
Dependencies: other mods it needs to run.
Platforms: whether it is available on Xbox and PlayStation as well as PC.

Nothing gets uploaded by hand. Unlike older Arma games, a Reforger server downloads mods straight from the Workshop when it starts.

Step 1: Add mod IDs to config.json

Open config.json and find the game section. Add a mods array (or extend the existing one):

{
  "game": {
    "name": "Friday Ops",
    "scenarioId": "{ECC61978EDCC2B5A}Missions/23_Campaign.conf",
    "maxPlayers": 32,
    "mods": [
      {
        "modId": "1234567890ABCDEF",
        "name": "Example Weapons Pack"
      },
      {
        "modId": "FEDCBA0987654321",
        "name": "Example Map",
        "version": "1.0.4"
      }
    ]
  }
}

Field	Required	What it does
`modId`	Yes	The GUID from the Workshop page
`name`	No	A label for you. The server identifies mods by ID only
`version`	No	Pins an exact version. Leave it out to always get the latest

Mind the JSON: every entry except the last needs a comma after its closing brace, and IDs and names go in double quotes. One misplaced comma and the server refuses to start, so run the file through a JSON validator if you are unsure. Bohemia's server config documentation lives on the Bohemia Interactive community wiki.

Step 2: Restart and watch the console

On startup the server resolves each mod ID against the Workshop, downloads anything missing or outdated, and loads it. The console shows every download and then the addons being loaded. Large mod lists take a while on the first start, after which only updates are downloaded.

Players do not need to install anything first. When they join, the game compares their mods with the server's list and downloads what is missing.

Arma Reforger soldiers moving with vehicles across Everon, the kind of battle modded servers add weapons and maps to

Should I pin mod versions?

Leaving out version means the server always takes the latest release on restart. That is right for most groups, because players also pull the latest version and everyone matches.

Pin a version when:

An update broke something and you want to stay on the last good release until it is fixed.
You run scheduled operations and do not want a mod changing between briefing and mission.

The catch: if you pin an old version and the author has removed it, or players already have a newer one, joins can fail. Unpin as soon as the fix is out.

How do I play a modded scenario?

Many mods add their own missions or maps, and the server needs that scenario's ID in scenarioId. Scenario IDs look like {ECC61978EDCC2B5A}Missions/23_Campaign.conf (Conflict on Everon). To find the ID of a modded scenario:

Add the mod to mods and restart.
Read the console. The server can list every available scenario, including ones added by mods (on a self host, start it once with the -listScenarios parameter; Bohemia notes Workshop scenarios only appear in that list when no scenario is being loaded).
Copy the full ID, braces included, into scenarioId and restart again.

If you set a modded scenario ID but the mod is not in the mods list, the server cannot find the mission and will not start.

Can console players join a modded server?

Only if every mod supports their platform. Reforger crossplay is set in config.json (the crossPlatform option, or a supportedPlatforms list), and console players can only join when every mod on the server is published for their platform. PlayStation has the strictest rules for user made content, so check each mod's platform list before promising PS5 players a modded server. A server that must include PlayStation is often easiest kept vanilla.

Why won't my modded Arma Reforger server start?

Symptom	Likely cause	Fix
Server stops right after reading the config	JSON syntax error	Check commas, quotes and brackets
"Can't find addon" or a mod download error	Wrong ID, or the mod was removed or made private	Copy the ID again from the Workshop page
A dependency "can't be added"	A dependency is missing or failed to download	Add the dependency's mod ID to the list too and restart
Mission fails to load	`scenarioId` points at a mod that is not loaded	Add the mod, or switch back to a vanilla scenario
Server starts but crashes on load	Two mods conflict, or one is outdated for the game version	Remove mods one at a time until it loads, then report it to the author
Players kicked with an addon load error	Players have an old or broken copy of a mod	Have them delete the mod in the in game Workshop and rejoin, and restart the server after mod updates
Stuck downloading on join	Very large mods or a slow Workshop	Wait, or trim the list

Game updates are the most common cause of sudden breakage. After a Reforger patch, many mods need updating by their authors. Keep the server and mods updating automatically, and if the server will not start after a patch, temporarily remove recently updated mods.

How many mods can a Reforger server run?

There is no hard number. Each mod adds download size for players and memory on the server, and big map or vehicle packs cost the most. A vanilla Conflict server for up to 32 players runs well on 8 GB. Move to 12 GB for 64 players or a decent mod list, and 16 GB for large modded servers pushing toward 128 players.

FAQ

How do I add mods to an Arma Reforger server?

Copy each mod's ID from the Reforger Workshop, add it to the mods array in the game section of config.json, and restart. The server downloads the mods itself.

Do players need to download mods before joining?

No. The game downloads the server's mods when players join. Subscribing ahead of time only saves time on a big list.

Where do I find an Arma Reforger mod ID?

On the mod's Workshop page, in game or on reforger.armaplatform.com. It is a 16 character code of letters and numbers.

Do I need to add mod dependencies to config.json?

If the log says a dependency cannot be added, yes: list that dependency's ID as well. Listing dependencies explicitly does no harm and makes the mod list easier to check.

Can Xbox players join a modded Reforger server?

Yes, if crossplay is enabled and every mod on the server is available on Xbox. Otherwise only PC players can connect.

Mods on a hosted Reforger server

On a GamezServers Arma Reforger server, config.json is open in the file manager, so adding a mod is a paste and a restart. Automatic Updates keeps the server and its mods current, the panel holds the scenario ID, and the console prints every scenario ID available, modded ones included. Back up before a big mod change, and see how to host an Arma Reforger server for crossplay and admin setup.