Fix “Unknown account username given” on a Project Zomboid Server
Build 42.19 multiplayer login, Open setting, and whitelist account setup.
Read the exact error text first
Unknown account username given usually means a closed server did not accept the username as an existing or allowed account.
The most common cause is that an admin never created the account. A capitalization mismatch can also produce this message on a closed Steam server.
This is not the same failure as an invalid username, a non-ASCII username, a wrong password, or a missing account password.
Stripping special characters or changing capitalization is not the first fix for this message.
Match the exact login error
| Exact message | What it means | Correct next step |
|---|---|---|
Unknown account username given |
A closed server did not find this exact username, and no Steam-ID allow-list exception applied. | Confirm the stored spelling and capitalization, then use the Open / whitelist decision tree below. Ask an admin for /adduser if the account was never created. |
Invalid username given |
The name fails format checks (length, banned characters, reserved prefixes, or word filter). | Use 2–20 characters and avoid ; , . ' " ? \ / @ $. This is not the same error as an unknown account. |
Username contains non-Ascii characters. |
The name uses non-ASCII characters and the server does not allow them. | Switch to an ASCII account name, or have the admin enable AllowNonAsciiUsername if that is intentional. |
Wrong username or password given |
An account with that name exists, but the password does not match, or the spelling/capitalization is not the stored form. | Retry the known password and stored account spelling carefully. An admin can run /setpassword. |
An account password is required |
This server expects an account password and none was provided. | Enter the account password field as well as any separate server password. |
An account with that username already exists |
Someone is trying to create a name that is already taken on this server. | Use the existing account and password, or pick a different unused name if you are creating a new one. |
Game account username is not the same field as Steam profile name. The connect dialog asks for the server’s account username and account password. Alex and alex cannot be two separate accounts, but login still expects the capitalization stored by the server and may reject a differently cased entry.
Player checklist for the unknown-account message
- Copy the full error text. If it is not exactly
Unknown account username given, use the table above instead of this section. - Use the stored account spelling. Type the name you were given or have used before, including its capitalization. Case variants are not separate accounts, but login can reject a form that does not match the server’s stored username.
- Fill both password fields correctly. Server password (if the host set one) is separate from your personal account password.
- Ask the host whether the server is open or closed. On a closed server, an ordinary username/password account must usually be created by an administrator. A deliberate Steam-ID allow list or host exception can bypass that; Steam friendship alone does not.
- If the host says your account exists, recheck spelling only. Spaces, trailing characters, and case all matter. Do not keep creating alternate names.
What not to do
Do not keep changing case to “test” the login, delete the entire
Zomboid folder, or treat a Steam name change as a server fix.
Random new account names can leave multiple half-created entries and make the real password harder to recover.
Open and account decision tree (for hosts)
Open=true
A valid new username with an account password may self-register, subject to the server password, MaxAccountsPerUser, bans, and other connection checks. After a successful join, the new account is saved to the server whitelist.
Open=false
For an ordinary username/password login, an administrator must create the account first. A name with no matching account normally receives Unknown account username given.
Steam-ID exceptions
On a Steam server, a Steam ID already on the whitelist or host allow list can pass the closed-server gate and may register the supplied username. Host/admin connections are handled separately.
Legacy option warning
Older guides still mention AutoCreateUserInWhiteList. On Build 42.19 that option does nothing—do not add it to your .ini as a fix.
| Open | Matching account | Steam-ID exception | Typical result | Admin action |
|---|---|---|---|---|
true |
Yes | Not required | The stored password and authentication method are checked. | Reset the password only if the existing credentials were lost. |
true |
No | Not required | A valid username and non-empty account password can create an account on successful join. | Watch MaxAccountsPerUser and use a server password if the server should not be public. |
false |
Yes | Not required | The player must use the stored spelling and password. | Use /setpassword if the password must be reset. |
false |
No | Yes | An allowed Steam ID may pass the closed-server gate and register the supplied username. | Review the host/Steam-ID allow list before assuming the username row is the only gate. |
false |
No | No | Unknown account username given. |
Create the account with /adduser "username" "password". |
Summary: Open=true permits self-registration and saves successful new accounts;
Open=false normally requires a pre-created account, with explicit Steam-ID and host/admin exceptions.
Administrator commands that fix the error
Run these from the in-game admin chat or the dedicated-server console after you have admin access. Quote names that contain spaces.
/adduser "PlayerName" "TemporaryPassword"
/addusertowhitelist "PlayerName"
/removeuserfromwhitelist "PlayerName"
/setpassword "PlayerName" "NewPassword"
/changepwd "OldPassword" "NewPassword"/adduser "username" "password"creates a new user on a whitelisted server. The password argument is optional in the command help, but giving one avoids an unprotected account./addusertowhitelist "username"adds an already-connected, passworded user that does not yet have a whitelist row. It is not a required follow-up to/adduser./removeuserfromwhitelist "username"removes a user from the whitelist./setpassword "username" "newpassword"is the admin reset when a player lost the account password./changepwd "previouspassword" "newpassword"is for a player changing their own password.
Closed-server workflow that works
1) Set
Open=false if you want a private server.
2) Create each player with /adduser "ExactName" "SharedOrPrivatePassword".
3) Tell the player the exact spelling and password.
4) Do not run /addusertowhitelist afterward—the /adduser command already created the whitelist row.
5) Reserve /addusertowhitelist for an already-connected passworded user that genuinely has no row. Restart only after offline .ini edits; accepted chat commands apply immediately.
Account name rules players must follow
- Length: at least 2 characters after trimming leading/trailing spaces, and at most 20 characters.
- Do not use:
; , . ' " ? \ / @ $or a null character. - Reuse the capitalization stored by the server.
Alexandalexcannot be registered as separate accounts, but entering the non-canonical case can still be rejected during login. - Non-ASCII names are blocked unless the server enables
AllowNonAsciiUsername. - The exact name
adminis reserved for the administrator path; other names beginning withadminare rejected, and the server word filter can block additional names.
Where hosts change Open and whitelist options
Windows dedicated / local host data
%UserProfile%\Zomboid\Server\<server-name>.ini
%UserProfile%\Zomboid\Server\
%UserProfile%\Zomboid\Logs\macOS and Linux
~/Zomboid/Server/<server-name>.ini
~/Zomboid/Server/
~/Zomboid/Logs/- In the
.ini, reviewOpen=,Password=,AllowNonAsciiUsername=, andMaxAccountsPerUser=. Ignore old instructions that tell you to addAutoCreateUserInWhiteList=; it is not a working Build 42.19 option. - Back up the whole
Zomboid/Serverfolder before hand-editing. A bad save can lock everyone out. - After offline
.iniedits, restart the server so the new policy loads. - Before sharing logs, remove server passwords, RCON secrets, public IPs, and Steam IDs.
Related fixes that are not this error
- Wrong server password produces a separate “wrong server password” style failure, not unknown account.
- Mod or build mismatches usually fail later with version or checksum messages, not this login string.
- Steam friendship or a generic invite does not replace a missing account on an
Open=falseserver; only an actual host/Steam-ID allow-list entry is an exception.
For private-server policy setup, see the dedicated server whitelist guide. For broader host operations, use the server administrator checklist and the server setup guide. After you can connect, the first-day survival roadmap covers what to do in the first multiplayer session.
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