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Project Zomboid Error 4 Then Error 6 After Character Creation: Workshop Mod Download Stall

Project Zomboid Guide • Updated May 26, 2026

Project Zomboid Error 4 Then Error 6 After Character Creation: Workshop Mod Download Stall

One of the most common support tickets on heavily-modded Project Zomboid servers is the player who gets through password and character creation, then sees the loading screen flash up two errors in sequence — error 4 followed by error 6 — and is dumped back to the main menu. The server is fine. The failure is on the joining client, and the cause is almost always Steam Workshop trying to download too many mods at once and timing out on one of them.

The Symptom in the Player's Words

A real support message from this week:

"Hey there, i keep getting error 4 and then 6 and then can't joing my server. I havn't joined before. It lets me create my character but then can get past the next loading screen."

The pattern is consistent: the connection completes, the server accepts the join, the mod list pushes to the client, then the loading screen stalls. After a timeout the client throws error 4, then error 6, then closes the connection.

Verbatim Error Strings the Client Sees

Connection lost: error 4
Connection lost: error 6

Variants seen in PZ client logs and player reports include:

error subscribing to workshop item
0MB unnamed mod
Mod <id> is missing

The Steam client side often shows:

Failed to subscribe to workshop item: Timeout

Verbatim Server Configuration That Triggers It

On a server that consistently triggers this failure pattern, the servertest.ini file at ~/prz/bin/Zomboid/Server/servertest.ini typically contains a long semicolon-delimited list:

Mods=autotsartrailers;AquatsarYachtClub;ATA_Samara;ATA_Bus;ATA_Dadge;ATA_VanDeRumba;ATA_DeLorean;ATA_Mustang;ATA_Mustang_x2;ATA_Mustang_x4;...
WorkshopItems=2282429356;2392987599;2850439818;2592358528;2743496289;2811232708;2963237571;...

On real customer deployments running this pattern, the workshop content directory holds 80–100 mod subdirectories:

$ ls ~/prz/bin/steamapps/workshop/content/108600/ | wc -l
84

That count is the diagnostic anchor. Below 20 mods this pattern is uncommon. Between 20 and 50 it appears occasionally. Above 50 it is the default failure mode for any new player joining.

The server is not the problem. The server downloads its mod list cleanly because it issues sequential SteamCMD requests with no rate limit. The client uses the Steam client's auto-subscribe path, which queues all subscriptions in parallel and trips the rate limiter when the list is large.

Why This Happens

Project Zomboid's join handshake sends the joining client the server's full mod list. The PZ launcher hands that list to the Steam client and asks Steam to subscribe to each Workshop item. With 5–10 mods the parallel subscribe path works. With 80+ mods, several side effects compound:

  • Steam Workshop's subscription API rate-limits clients that fire too many requests in a short window.
  • Larger mods (vehicles, map packs, total conversions) can take 30–90 seconds to download each.
  • If any single mod download times out, the loading screen stalls until the full timeout hits, then throws error 4.
  • The Steam client retries the failed mod once, fails again, and PZ throws error 6 as the close-out.

The same pattern triggers when a mod ID in the server's WorkshopItems= list points to a mod that has been deleted from the Workshop. The server can still load it from its local cache, but the client cannot subscribe to a deleted item and the handshake hangs on that one ID.

Phase 1: Client-Side Fixes (Try in Order)

  1. Subscribe via a Steam Collection. Ask the server admin to publish a Steam Collection containing every mod in WorkshopItems=. Subscribe to the collection in one click before joining. Steam batches the downloads more efficiently than the in-game subscribe path.
  2. Verify integrity of game files. Steam → Library → right-click Project Zomboid → Properties → Installed Files → Verify integrity of game files. This forces Steam to re-check Workshop content metadata.
  3. Force a Workshop re-download. Close Project Zomboid. Delete <steam-library>/steamapps/workshop/content/108600/ and <steam-library>/steamapps/workshop/appworkshop_108600.acf. Relaunch PZ and let it re-sync the Workshop folder from the server's mod list.
  4. Restart the Steam client. A stale Steam client process is the second-most-common cause after rate limiting. Quit Steam fully from the system tray, then relaunch and try joining again.
  5. Disable any VPN. Some VPN exit points are rate-limited harder by Steam Workshop than residential IPs.

Phase 2: Server-Side Checks the Admin Should Run

  1. Mods tab vs servertest.ini parity. Open the panel's Mods tab. Every entry there should also appear in ~/prz/bin/Zomboid/Server/servertest.ini on both the Mods= and WorkshopItems= lines. A mod present in one list but not the other is the most reliable cause of permanent join stalls.
  2. Hunt for deleted Workshop IDs. Take each ID from WorkshopItems= and check https://steamcommunity.com/sharedfiles/filedetails/?id=<id>. A 404 or "Item not found" means the mod was deleted by its author. Remove that ID and its matching Mods= entry, then restart.
  3. Count the live mod folders. 
    ls ~/prz/bin/steamapps/workshop/content/108600/ | wc -l
    A number above 50 is a heavy modpack and you should consider splitting it into a "core" and "optional" tier.
  4. Test with a clean client. Have a player on a known-good connection (residential, no VPN, fresh Steam restart) try to join. If the clean client succeeds, the failures are environmental on the original player's side and the server is healthy.

Verifying the Fix

The healthy join sequence in the server's ~/prz/bin/Zomboid/Logs/<date>_DebugLog-server.txt looks like this:

LOG  : General  ...> Connection from ... accepted.
LOG  : General  ...> sending mod list to client <steamid>
LOG  : General  ...> client <steamid> ready, sending world data
LOG  : General  ...> player <name> connected.

If the server log shows "sending mod list to client" but no "ready" line within two minutes, the client is stuck downloading mods. That is your error-4-then-6 case proven from the server side.

Long-Term Mitigation

  • Keep mod count under 50 if you can. Most failures vanish below that threshold even without other changes.
  • Publish a Steam Collection for the server. One-click subscribe is the single biggest reduction in join failures on heavy modpacks.
  • Pin mod versions. If a single mod auto-updates and breaks compatibility, every joining client hits the failure. Some host panels expose mod-version locking; use it if available.
  • Run a mod audit monthly. Deleted mods accumulate over time. A 12-month-old server can have three or four IDs that no longer resolve, each one a permanent stall vector for new players.

When to Escalate

Contact support if:

  • Mod count is below 30 and players still consistently hit error 4 / error 6.
  • The server log shows "sending mod list" but no subsequent "ready" lines across multiple clients on different networks.
  • You have already audited WorkshopItems= for deleted IDs and parity-checked against the Mods tab.

That combination points at a server-side handshake bug rather than the modpack scale issue.

For Project Zomboid servers with built-in Workshop sync monitoring and one-click mod parity validation, see Project Zomboid server hosting on Supercraft. The panel surfaces deleted Workshop IDs automatically and warns you before they break new joins.

Last updated: 2026-05-26.

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