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---
id: uefn-epic-update-troubleshooting
title: Fortnite and UEFN update will not install
tags:
  - launcher
  - update
  - install
  - verify
  - fortnite
  - uefn
when_to_use: Before diagnosing a Fortnite or UEFN update that will not install on Windows. Call get_skill('uefn-epic-update-troubleshooting') first. Covers a false still-running lock, install-helper verify failures, and a follower UEFN update blocked because Fortnite is Pending. Verify is the repair. Do not edit files inside the game install.
---

# Fortnite and UEFN update will not install

Call this skill **before** diagnosing a Fortnite or Unreal Editor for Fortnite
update that will not install on Windows. This page is the hosted playbook.
Do not invent a second one.

It tells you what the failure is, which signature you are on, and which
existing tool or Epic control does the next step. It does not install the
game for you.

LOOKUP ORDER:

1. `get_skill('uefn-epic-update-troubleshooting')` (this page).
2. Read-only snapshot: client script `scripts/Get-EpicUpdateState.ps1`
   (uefn-mcp). If local `tools/list` has a tool that runs that script,
   call the tool. Do not write a second snapshot.
3. Epic Games Launcher **Verify** (Library, three dots, Manage, Verify)
   for the app the snapshot names. There is no hosted tool that clicks
   Verify.
4. `search_verse_kb` `mode=docs` for the Epic help page that matches the
   code on screen. `mode=howto` for the public guide
   `fortnite-uefn-update-will-not-install`.

A stale **MCP client** is not this job. That one-liner is
`get_skill('uefn-welcome')`. Depot sync is `get_skill('uefn-p4')`.
Editor bind and inspect is `get_skill('epic-valkyrie-mcp')`.

## What this covers, and what it does not

Use it when the Epic Games Launcher will not finish an update or install
of Fortnite or UEFN on Windows: the button says the app is still running,
an install error code is on the tile, the update retries and quits, or
UEFN sits queued while Fortnite never leaves an interrupted update.

Do not use it for Mac, console, mobile, or cloud play. Do not use it for
sign-in, two-factor, payment, or bans. Do not use it for Verse compile
errors, devices, or project content. Do not use it to change files inside
a Fortnite or UEFN install directory.

**Verify is the sanctioned repair** for damaged or missing game files.
Do not edit, delete, or replace files inside the Fortnite or UEFN install
directory. That includes pak files, `Engine.ini`, and anything else under
the game folder. Clearing the launcher **webcache** (below) is Epic's
launcher-cache step. It is not a game-folder edit.

## Snapshot first

The logs are on the workstation. This Worker cannot see them. From the
uefn-mcp checkout, in Windows PowerShell:

```
powershell -NoProfile -File scripts/Get-EpicUpdateState.ps1
```

Read the script comment header before you add a switch. The script is
read-only: it prints launcher and install-helper state and does not
install, verify, or delete. There is no hosted route for it. Do not add
one. A missing click-Verify action would be a future **client** command
on that same workstation, not a Worker tool.

Trust the snapshot for which processes exist, which error strings are in
the install-helper `UE-*.log`, and whether the main Fortnite install is
Pending. Then take one signature below. Do not guess a signature the
snapshot does not show.

## Signature A — launcher says it is still running

The tile says Fortnite or UEFN is still running, so Update and Verify
stay disabled, but the snapshot shows no Fortnite or UEFN process.

1. If the snapshot shows a real game or editor process, close that app.
   Then use the launcher system-tray **Exit**. Ending the window is not
   enough.
2. If the snapshot shows `EpicGamesLauncher`, `EpicWebHelper`, or
   `EpicOnlineServicesUserHelper` still alive after Exit, end those
   processes in Task Manager, then start the launcher once.
3. If the snapshot shows **none** of those processes and the UI still
   says the app is running, the lock is stale. A staged launcher
   self-update is the usual cause: the launcher has an update of its
   own waiting to apply, and the running-app flag survives the restart
   that never finished. Start the launcher again and let **its** update
   finish before you retry the game update.

Epic's public help does not describe this false lock (gap). The symptom
is reported on the Epic Developer Community (launcher shows Fortnite and
UEFN still running after they were closed). Epic **does** document the
launcher's own update failing for disk space: `SU-DS01`, `SU-DS02`,
`SU-DL01`, and `SU-FC01` through `SU-FC05` mean the drive is full. Free
space with Windows disk cleanup or by moving other data. Do not delete
files inside the game install to make room. Then start the launcher
again so the self-update can finish.

`SU-PQR*` / `SU-PQE*` ("necessary prerequisites have failed") is a
different launcher self-update failure. Epic's article says run the
launcher as administrator, reinstall the Visual C++ redistributables,
and confirm the install folder allows Read and Write. Follow that
article. Do not apply it to a game-file verify failure.

## Signature B — IS-EO-ih_early_exit and BuildVerifyFail

The tile retries and stops with `IS-EO-ih_early_exit`. The install-helper
`UE-*.log` in the snapshot shows `BuildVerifyFail` with `BV02` or `BV05`.

Epic has not published a help page for `IS-EO-ih_early_exit` (gap).
Treat the early exit as the helper quitting. The verify code in that
log is the cause. Repair that code. Do not edit `Engine.ini`. Community
posts suggest download throttling, folder permissions, or an `Engine.ini`
under the launcher config. Those posts disagree with each other, and
none of them is Epic's published fix. Do not follow the ini edit.

| Code in the log | Epic's published meaning | Next step |
| --- | --- | --- |
| BV02 / IS-BV02 | File missing or invalid | `chkdsk` on the install drive (Administrator Command Prompt, `chkdsk <drive>: /r /f`), then Windows Memory Diagnostic. Then **Verify**. |
| BV03 / IS-BV03 | Install is corrupt | Confirm the volume is NTFS (This PC, drive Properties). Run Windows Memory Diagnostic. Epic also says try another drive. Then **Verify**. |
| BV04 / IS-BV04 / IS-IN-BV04 | Build verification failed, hash mismatch | NTFS, Windows Memory Diagnostic, and install on the drive that has the compatible OS. Then **Verify**. |
| BV05 on Fortnite or UEFN | Epic has no Fortnite article for this code (gap) | **Verify** Fortnite or UEFN. Do not use the Unreal Engine article below. |

`IS-IN-BV05` on **Unreal Engine** is a different product. Epic's article
says uncheck **Engine Source** on the engine install options. That step
does not exist for Fortnite or UEFN. Do not tell a Fortnite or UEFN
update to uncheck Engine Source.

`chkdsk` and Windows Memory Diagnostic are the Windows tools Epic names
on the BV02 and BV04 pages. They are not MCP tools. Verify is still
required after they finish: Epic's verify article is the repair for
files that do not match the manifest.

## Signature C — UEFN cannot move because Fortnite is Pending

UEFN is a follower app. The launcher app id is `Fortnite_Studio`. It
does not update while the main Fortnite install is **Pending** after an
interrupted download.

1. Read the snapshot. If Fortnite is Pending, do not start with UEFN.
2. In the launcher, resume the Fortnite update. If resume is not
   offered, **Verify** Fortnite.
3. When Fortnite is no longer Pending, update or Verify UEFN.

Do not delete `Manifests\*.item` files. Do not edit
`LauncherInstalled.dat`. Community reports of `IS-0009` ("could not
read installation information") start after those files were removed
by hand, and Epic has no help page for `IS-0009` (gap). If the tile
offers Library **Uninstall**, use that, then **Install**. If the tile
stays on Update failed after Uninstall, stop. That record is Epic
Support's, not a file edit.

A queue that never starts, with no error and no Pending flag, is also
thin in Epic's docs (gap). Exit from the tray, confirm the snapshot
shows the helper processes gone, start the launcher, and resume. An
Epic Developer Community thread (UEFN stuck on Queued) ended in Verify,
then Uninstall and Install from the Library. Verify first.

## Other codes the tile can show

Match the code in the snapshot. Then `search_verse_kb` `mode=docs` if
you need the article text.

- **IS-DS01** — not enough space before the install. Free space, or
  choose another volume with the launcher's Browse button on Install.
- **IS-DS02** — ran out of space during the install. Same as DS01.
  Epic also lets you drop optional Fortnite features: Library, three
  dots, Options, uncheck what you do not need, Apply. That is a
  launcher control. It is not a hand edit of the install.
- **IS-MF02-5, IS-MF03-5, IS-MF02-32, IS-MF02-225** — BattlEye or Easy
  Anti-Cheat did not start. This is a **launch** failure after files
  are present, not a BuildVerifyFail. Epic says set those two services
  to Automatic (Delayed Start), then clear the launcher webcache, then
  run the launcher as administrator.
- **LS-0006** and **IS-INFO-DSTCVPAT** — the launcher cannot install or
  update. Epic's order: run the launcher as administrator, clear the
  launcher webcache, Library Uninstall, then Install. Epic's last
  resort is to Exit the launcher and delete the **whole** game folder
  (default `C:\Program Files\Epic Games\`), then Install again. That is
  an uninstall, not an edit of files inside the folder. If Verify is
  available, run Verify before that last resort.
- **Launcher webcache** — Epic's cache clear, used when a download size
  looks wrong and by the LS-0006 / MF articles. After tray Exit, under
  `%localappdata%\EpicGamesLauncher\Saved\`, delete only `webcache`,
  `webcache_4147`, and `webcache_4430` (whichever exist). Start the
  launcher. Do not delete the game directory in this step.

## Verify

Epic's verify article:

1. Open the Epic Games Launcher.
2. Find the game in the Library.
3. Click the three dots on that row.
4. Select Manage.
5. Click Verify.
6. Wait until validation finishes. Saved data is not part of this
   repair.

Run it on Fortnite and on UEFN separately when both failed. Verify
stays disabled while signature A is still true. Clear that lock first.

No hosted tool clicks Verify. Do not invent `verify_game` on this
Worker. If a client tool is added later whose description says it
starts this same Library Verify, call that tool. Until then the person
at the machine clicks Verify.

## EXAMPLE — v42.30 rollout

EXAMPLE only. Not a rule that these failures belong to one version.

During the v42.30 rollout the same three signatures showed up together.
The launcher said Fortnite and UEFN were still running while no game
process existed (a staged launcher self-update). The install helper
retried `IS-EO-ih_early_exit` because `UE-*.log` contained
`BuildVerifyFail` BV02 or BV05. UEFN (`Fortnite_Studio`) could not
update because the main Fortnite install was Pending after an
interruption. Later versions can show any one of those signatures on
its own. Diagnose from the snapshot, not from the version number.

## Sources

Epic help (primary):

- Verify: `https://www.epicgames.com/help/c-202300000001619/c-5719341627163/a202300000017217?lang=en-US`
- IS-BV02: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-bv02-file-missing-or-invalid-a000084896`
- IS-BV03: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-bv03-install-failed-the-installation-is-corrupt-a000085707`
- IS-BV04 / IS-IN-BV04: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-bv04-or-is-in-bv04-build-verification-failed-due-to-mismatched-hash-a000084878`
- IS-IN-BV05 (Unreal Engine Engine Source only): `https://www.epicgames.com/help/en-US/epic-games-store-c-202300000001639/error-messages-c-202300000001736/i-encountered-error-code-is-in-bv05-when-trying-to-install-unreal-engine-a202300000013584`
- IS-DS01: `https://www.epicgames.com/help/c-202300000001639/c-202300000001736/is-ds01-out-of-disc-space-before-trying-to-install-a-game-a202300000015357`
- IS-DS02: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-ds02-ran-out-of-disc-space-during-installation-a000084873`
- SU-DL01 / SU-DS01 / SU-DS02 / SU-FC0*: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/su-dl01-su-ds01-su-ds02-su-fc01-su-fc02-su-fc03-su-fc04-or-su-fc05-error-a000087217`
- IS-MF02 / IS-MF03: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-mf02-5-is-mf03-5-in-fortnite-is-mf02-32-or-is-mf02-225error-a000087214`
- LS-0006: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/ls-0006-installation-failed-a000084968`
- IS-INFO-DSTCVPAT: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_ErrorCodes/is-info-dstcvpat-error-appears-when-trying-to-update-a-game-a000085705`
- Misreported download size, Verify, and webcache: `https://www.epicgames.com/help/en-US/c-Category_EpicGamesStore/c-EpicGamesStore_LauncherSupport/why-do-download-file-sizes-seem-larger-than-normal-especially-after-an-update-in-epic-games-launcher-a000086940`

Docs gaps, where community agrees on the symptom and Epic is silent on
the mechanism:

- False "still running" after close: `https://forums.unrealengine.com/t/epic-games-launcher-glitch/2724046`
- UEFN stuck Queued: `https://forums.unrealengine.com/t/uefn-update-queue-stuck/2625428`
- IS-0009 after manifest edits (do not repeat those edits): `https://forums.unrealengine.com/t/unable-to-resolve-uefn-is-0009-update-failed/2642718`
- `IS-EO-ih_early_exit` community thread (do not follow the ini edit): `https://www.reddit.com/r/FortNiteBR/comments/1uh99uy/error_code_iseoih_early_exit/`

No Epic YouTube video was found that contradicts the help articles
above. An X search on 2026-10-06 for `IS-EO-ih_early_exit` and
`Fortnite_Studio` returned no posts. Prefer the help articles when a
community post disagrees.