DayZ "Signature Check Timed Out" Kick? How to Fix It

If players get kicked from your DayZ server with "Signature check timed out" or "Modified data", the server could not verify one of their mod files. On a community server that almost always means a mod's .bikey file is missing from the server's keys folder, or the player and the server have different versions of a mod. Copy the missing key, update the mods on both sides and restart, and the kicks stop. This guide covers every cause in order.

The messages

Players usually see one of these when they get kicked a few seconds after joining:

• Signature check timed out
• Modified data (sometimes followed by a file name)

Both come from DayZ's signature check, which compares each mod file (.pbo) the player loads against its signature (.bisign) and the keys (.bikey) the server trusts. If any file fails, the player is kicked.

Quick fix

1. Stop the server.
2. For every mod in your -mod= list, copy the .bikey file from the mod's keys (or Keys) folder into the server's keys folder.
3. Make sure the server has the latest version of every mod.
4. Start the server.
5. Players open the DayZ Launcher, let it update their mods, and join through the launcher.

Cause 1: A mod's key is missing from the server

This is the big one. Each Workshop mod ships a key: a file ending in .bikey inside the mod's keys folder, for example in @CF/keys/. The file name varies by mod. The server only accepts mod files signed by keys in its own keys folder. Add a mod without its key and every player who loads that mod gets kicked.

To fix it:

1. Open the mod's folder in the server directory, such as @CF or @DayZ-Expansion-Bundle.
2. Open its keys folder (some mods name it Keys or key).
3. Copy every .bikey file into the server's top level keys folder.
4. Restart. Keys are only read when the server starts.

Do this for every mod, including ones bundled together. Mod packs often contain several keys.

On GamezServers, adding a Workshop mod in the panel does this for you: we download the mod, load it with the right -mod parameter and copy its .bikey into the keys folder, so this cause is covered for mods added that way. If you uploaded a mod by hand through the file manager or SFTP, copy its key yourself.

Cause 2: Mod versions do not match

When a mod author pushes an update, players' launchers update it right away, but the server keeps its old copy until it is updated too. The files no longer match, and players get kicked. It also happens the other way round, when the server has the new version and a player has not updated yet.

To fix it:

• Server side: update the mod and restart. Self hosters download it again with SteamCMD (+workshop_download_item 221100 <mod id>) and copy the new files and key over the old ones. On a hosted server, updating the mods and restarting usually fixes it.
• Player side: open the DayZ Launcher, go to Mods, and let it update. If a mod is stuck, unsubscribe and subscribe again on the Workshop.

Big DayZ updates often come with a wave of mod updates, so expect this after patches.

Cause 3: The player loads extra mods

Players who launch DayZ with mods your server does not run can be kicked, because the server has no key for those files. This happens a lot when someone jumps from a different modded server.

Tell players to join through the DayZ Launcher's Servers tab or Direct Connect. The launcher loads exactly the mods your server runs and nothing else.

Cause 4: Corrupted files on the player's PC

If one player gets kicked and everyone else is fine, their files are probably damaged. They can:

1. Verify DayZ in Steam: right click DayZ, Properties, Installed Files, Verify integrity of game files.
2. Unsubscribe from the server's mods, then join through the launcher so it downloads them fresh.

Cause 5: Load order or a broken mod install on the server

A mod folder that was only partly uploaded, or a wrong -mod= order, can make the server load mismatched files. Check that:

• frameworks such as Community Framework come first in -mod=,
• mod names in the launch line match the folder names exactly (Linux is case sensitive),
• every mod folder contains its addons folder with .pbo and .bisign files.

How to install mods on a DayZ server covers load order and server side mods in detail.

Do not turn off signature checks

You may see old advice to change verifySignatures in serverDZ.cfg. Leave it at 2:

verifySignatures = 2;

Bohemia's own server config documentation says only 2 is supported, and signature checks are what stop players joining with modified files. Fix the keys instead.

Checking the server log

If you cannot tell which mod is the problem, open the latest .RPT or script log in the server's profiles folder right after a kick. It usually names the file that failed. The mod whose folder holds that file is the one with a missing key or old version. On a hosted server, you can open the logs in the Files tab.

FAQ

What does "Signature check timed out" mean in DayZ?

The server could not verify one of the player's mod files in time, usually because the matching .bikey is not in the server's keys folder or the versions do not match.

Why does only one player get kicked?

That player's files are outdated or corrupted, or they launched extra mods. Have them update mods through the launcher or verify the game files.

Do I need to restart after adding a key?

Yes. DayZ reads the keys folder only when the server starts.

Can I just set verifySignatures to 0?

No. Only 2 is supported, and it protects your server. Add the missing keys instead.