Published island fails server cook since Oct 29 (artifact linux-server-vm, content-service cook_failure) — same content played fine on Oct 28; Matchmaking Error for all players

General Issues and Bug Reporting
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Summary

Island 5892-8688-9966 (UEFN project BallistiicUnited2, creator Pan_T0m11). Since Oct 29, 2026 (~09:30 CET) every published release and every private version of this island fails when a player tries to join: “Preparing Island” runs ~4 minutes, then “Matchmaking Error”. The client log shows FailedToBuildManifestServer / errors.com.epicgames.content-service.cook_failure — “failed to cook module 2cb65c48-4a71-c064-680b-45941b5900b8 (artifact …:linux-server-vm) with error code errors.com.epicgames.cookplugin.cookfailure”. The identical content cooked and played without issues on Oct 28 (Release 86 / 87), and Launch Sessions (edit sessions, classic linux-server artifact) still cook the Linux server fine today. Only the published / private-version server cook with the “linux-server-vm” artifact fails. UEFN publishing validation, Windows client cook, Verse validation and Memory Calculation (99,418) all pass. The island is Listed, so every player gets Matchmaking Error 1.7.

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Publishing

Steps to Reproduce

  1. In Fortnite (v43.xx, PC), enter island code 5892-8688-9966 (published Release 87) or the private version code 9015-1898-7445.
  2. “Preparing Island” is shown for ~4 minutes (first-join server cook).
  3. Join fails with “Matchmaking Error” (1.7). FortniteGame.log: “Starting cook for linkid Mnemonic=[9015-1898-7445] Version=[1] {EConsumerRole::Server - Linux}” followed by “LogMatchmaking: Error: [flow_failed] Content Beacon Encountered Fatal Error: FailedToBuildManifestServer - ContentBeaconV2.FailedToBuildManifestServer.Host … errors.com.epicgames.content-service.cook_failure … failed to cook module 2cb65c48-4a71-c064-680b-45941b5900b8 (artifact dad70bcc-900c-4067-a86c-8379e968e1c0:linux-server-vm) (cookJobId b6c0bd0a-c7c4-4149-b7c3-4803447b921b) with error code errors.com.epicgames.cookplugin.cookfailure”.
  4. Repeat with any older version of the island (e.g. Release 87 = 7392-2083-9728, which was played on Oct 28): same failure.
  5. Start a Launch Session from UEFN with the same project: the Linux server cooks successfully in ~2 minutes (classic linux-server artifact).

Expected Result

The server cook of a published / private version succeeds and the player loads into the island, exactly as it did on Oct 28, 2026 (Release 86 and 87 were played without any issue; no project change can explain the regression because even the untouched Release 87 now fails).

Observed Result

Every published and private version fails the “linux-server-vm” server cook since Oct 29 (~09:30 CET). Failed cooks (all module 2cb65c48-4a71-c064-680b-45941b5900b8):

  • 9015-1898-7445 (Oct 30 03:33 UTC): artifact dad70bcc-900c-4067-a86c-8379e968e1c0:linux-server-vm, cookJobId b6c0bd0a-c7c4-4149-b7c3-4803447b921b, RequestId 01A18ADB3A45778F9927425B638972D3
  • 5892-8688-9966 Version 87 (Oct 30 01:06 UTC): artifact 36160d8c-68e5-4ff6-a78b-2797f62c46e5:linux-server-vm, cookJobId e2db9938-8710-4c09-a643-adcd93349386
  • 2509-0849-9671 / Release 86 (Oct 30 00:07 UTC): artifact 67dc499a-381b-43e5-ac07-5fb9e99107e5:linux-server-vm, cookJobId 18280fac-ac0e-4601-8e1f-04b6adce5953, RequestId 01A18A220E0972D2BC6B722112177FE8
  • 6461-0706-5419 / Release 89 (Oct 29 20:39 UTC): artifact 4eed0062-8d66-46ea-8dcf-1d631c0a96cd:linux-server-vm, cookJobId b82a1e0c-4980-4786-9dd3-134a93ce3a51
  • 6707-0774-1615 / Release 88 (Oct 29 18:01 UTC): artifact 6ca7408b-4c8c-4ef5-8799-49a3f9fd9328:linux-server-vm
    Edit sessions (Launch Session) of the identical content cook the Linux server successfully (e.g. Oct 29 08:20 UTC, 2 min 10 s). UEFN publishing validation, Windows client cook, Verse validation and Memory Calculation (99,418 / 100,000) all pass; download size 344.6 MB. As a consequence the release “UNITED 5v5 | Search & Destroy” was also failed in content review with 1.14 (“does not function as intended”) on Oct 30 00:40 CET.

Platform(s)

All platforms (the failure is the server-side cook; reproduced from PC / Windows 11, Fortnite 43.xx, UEFN 43.xx).

Island Code

5892-8688-9966

Additional Notes

This looks related to the VerseVM server rollout: in the “[DONE] Verse VM test — Friday, September 11” thread (topic 2764537) several islands failed to matchmake or cook during the VerseVM test and it was confirmed to affect public and private UEFN sessions. Our island cooks fine on the classic linux-server artifact (edit sessions) and fails only on the linux-server-vm artifact. The project has ~90 Verse files and ~60 Verse devices; it also references Fab / Epic creator content packs (29 References/*.uref). Could you share the cook log for cookJobId b6c0bd0a-c7c4-4149-b7c3-4803447b921b (or 18280fac-ac0e-4601-8e1f-04b6adce5953) or tell us which asset / Verse construct the linux-server-vm cook rejects? We are ready to change whatever the new VM requires. A new release (private version 9015-1898-7445) is currently in content review; please also note that the 1.14 review failure of the previous release was caused by this cook failure, not by island content.