# In-place upgrade repair: when it is worth the 40 minutes

> How a repair install differs from a reset, what it keeps, and the two failure logs that tell you why it stopped.

**Tested on**

- Build: 26300.9457 / 26100.33650
- Edition: Pro (26H2) / Server
- Architecture: x64
- Evidence: E1
- Verified: 2026-10-29

## The short answer

An **in-place upgrade** reinstalls Windows over itself, keeping files, settings and most applications. It is the repair you want when:

- `sfc` and `DISM` cannot fix corruption,
- the component store is broken beyond repair,
- an update repeatedly fails and uninstalling it does not help,
- and you cannot afford a clean install.

It is **not** a reset. A reset removes apps; an in-place upgrade tries to keep them.

## What it keeps and what it loses

| Kept | Often lost |
|---|---|
| Files and folders | some drivers (reinstalled) |
| User accounts and profiles | apps with incompatible installers |
| Most desktop apps | apps that hook the shell deeply |
| Windows settings | some default app associations |
| Activation (digital licence) | third-party antivirus (usually removed) |

Take an image or at least back up the documents folder. "It keeps files" is a design intent, not a guarantee.

## Prerequisites that decide success

1. **Same or newer build** — the media must not be older than the installed build.
2. **Matching language and edition** — different edition means it becomes an upgrade, not a repair.
3. **Free space** — roughly 20GB plus the size of the old install.
4. **Disable third-party antivirus** for the duration.
5. **BitLocker suspended** — the upgrade reboots several times.

```powershell
# what you are running now
Get-ComputerInfo | Select-Object WindowsProductName,WindowsVersion,OsBuildNumber,OsArchitecture
# suspend BitLocker for the duration (re-enables after N reboots)
Suspend-BitLocker -MountPoint C: -RebootCount 3
```

## Run it

From mounted media or an extracted ISO:

```powershell
# from the root of the installation media
.\setup.exe /auto Upgrade /DynamicUpdate Disable /ShowOOBE None
```

- `/DynamicUpdate Disable` avoids waiting on network updates mid-setup.
- `/ShowOOBE None` skips the out-of-box experience.
- Without switches, the GUI offers **Keep personal files and apps** — that is the repair option.

If the option to keep apps is greyed out, the media does not match the installed edition/language. Fix the media, do not force it.

## When it fails, read these

| Log | Location | Contains |
|---|---|---|
| `setupact.log` | `C:\$WINDOWS.~BT\Sources\Panther\` | the whole setup trace |
| `setuperr.log` | same folder | only the errors |
| `setupact.log` (rollback) | `C:\$WINDOWS.~BT\Sources\Rollback\` | why it reverted |

`setuperr.log` is short; start there. Common causes: a driver blocking the upgrade, insufficient space, a language mismatch, or a pending reboot that was never completed.

## After it finishes

1. Check `winver` — the build should be identical or newer.
2. Confirm activation: **Settings → System → Activation**.
3. Reinstall the drivers that were removed (GPU, chipset, printer).
4. Resume BitLocker and verify protection: `manage-bde -status`.
5. Run Windows Update until clean.

> **Caution: An in-place upgrade is not a fix for malware**
>
> If the machine is compromised, a repair install keeps the user profile — and possibly the persistence. Malware removal needs a clean install or a verified scan, not a repair.

## When a clean install is the better answer

- The machine is being handed to someone else.
- The profile itself is corrupt (a new local profile and migration is the fix).
- You want a known-good state and have backups.
- The upgrade failed twice at the same stage.

## Related

- [Repair Windows system files](https://windows.homes/en/windows/fixes/dism-sfc/)
- [The Insider Programme](https://windows.homes/en/windows/update/insider/)
- [Clean install vs reset](https://windows.homes/en/windows/install/clean/)

## Lab boundary

E1. Setup switches and behaviour are Microsoft-documented. No repair upgrade was run on the lab VMs for this page.

## Sources

- [Microsoft Learn — Windows Setup command-line options](https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/windows-setup-command-line-options)
- [Microsoft Learn — Windows Setup automation overview](https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/windows-setup-automation-overview)
- [Microsoft Learn — Manage updates with Windows Update for Business](https://learn.microsoft.com/en-us/windows/deployment/update/waas-manage-updates-wufb)

---

Source: https://windows.homes/en/windows/update/inplace-upgrade/