Arma Reforger config.json Troubleshooting
When a server exits at startup or ignores settings, the cause is usually a small set of config problems. Work through these checks from top to bottom, or paste the file into the validator to catch most issues locally.
1. Invalid JSON
The most common failure is plain JSON syntax. JSON is strict:
- Trailing commas after the last object or array item are not allowed.
- Comments such as
//or/* */are not part of JSON. - Smart quotes from chat apps or word processors must be replaced with straight
"quotes. - Missing commas or brackets can make the reported error appear far from the actual mistake.
2. Mods listed in the wrong place
The mods array must be inside the game object. A top-level mods key parses fine and is then ignored, so the server starts vanilla with no useful error.
3. Malformed or duplicate mod IDs
Workshop mod IDs are 16 hexadecimal characters. Truncated IDs, IDs with spaces, or full URLs pasted into modId will not resolve. Duplicate entries are confusing and can hide version conflicts.
4. Port problems
- Ports must be numbers, not strings, and within
1 to 65535. - The game, A2S, and RCON ports must not collide.
publicAddressandpublicPortmust match your firewall and NAT forwarding.
5. Scenario ID mistakes
game.scenarioId must exactly match an available scenario in the form {GUID}Missions/File.conf. If a scenario comes from a mod, that mod must also be in your mod list.
6. RCON settings
If RCON is configured, it needs a valid port and a password. The official docs require the password to be non-trivial and contain no spaces. Remove the whole rcon object if you do not use RCON.