Migrate Slack to MSIX on Windows Endpoints

What the Slack MSIX migration Worklet does

This Automox Worklet™ replaces legacy Slack installs on Windows endpoints with the Slack MSIX package. Slack retired its Windows MSI and EXE installers in favor of MSIX, which leaves fleets carrying a mix of a machine-wide MSI, per-user MSI copies, and per-user Squirrel installs that update on their own schedule.

The Worklet acts only on endpoints that already have Slack. Evaluation looks for a machine-wide MSI whose DisplayName matches Slack (Machine - MSI) in the HKLM uninstall hive, a Squirrel install at %LocalAppData%\slack\Update.exe in any C:\Users profile, and per-user Slack uninstall entries in currently mounted HKEY_USERS hives. An endpoint that already has only the MSIX, or that has no Slack at all, is reported compliant and nothing runs.

Because the Automox agent executes scripts as SYSTEM in 32-bit PowerShell, the Worklet reads both the native 64-bit and the 32-bit registry views during detection, and relaunches itself in native 64-bit PowerShell through the Sysnative alias before it removes anything or calls DISM. That is what keeps a 64-bit machine-wide MSI from hiding behind WOW64 redirection.

Why move Slack from MSI and Squirrel to MSIX

Per-user Squirrel installs are the hard part of managing Slack on Windows. Each profile carries its own copy under AppData, updates itself outside your patch policy, and survives a machine-wide uninstall. A shared workstation can end up running four Slack versions with four different sets of fixes, and none of them show up where a machine-wide inventory looks.

The MSIX package changes that shape. One provisioned package serves every user on the endpoint, each user gets it at sign-in, and version state becomes something you can report on per endpoint instead of per profile. Removal is equally predictable, because there is one package to remove rather than a folder in every profile.

Migrating also settles the question of which install path an endpoint is on. Slack now ships the Windows desktop app as MSIX, so every endpoint left on the MSI or Squirrel path is a one-off you have to reason about separately. Running this Worklet against a device group converts the fleet in a single pass and reports the result per endpoint in the Activity Log.

How the Slack MSIX migration works

1. Evaluation phase: Reads the HKLM uninstall hive through both the native 64-bit and the 32-bit registry views for a machine-wide Slack MSI, checks every C:\Users profile for %LocalAppData%\slack\Update.exe without a .dead marker, and scans mounted HKEY_USERS hives for a per-user Slack uninstall entry. The check mounts no hives and changes nothing; an endpoint with only the MSIX, or with no Slack, is compliant.

2. Remediation phase: Relaunches in native 64-bit PowerShell through Sysnative, stops running Slack processes, uninstalls the machine-wide MSI with msiexec /x and clears any leftover uninstall key, then sweeps each profile: Update.exe --uninstall -s for Squirrel installs, removal of the Start Menu folder and desktop shortcuts, deletion of the slack folder, and cleanup of the per-user uninstall key, loading ntuser.dat when the user is signed out. It then downloads the x64 or arm64 MSIX from Slack and installs it for all users with Add-AppxProvisionedPackage -Online -SkipLicense.

Slack MSIX migration requirements

• Windows 10, Windows 11, or Windows Server builds that support MSIX provisioning through DISM, on x64 or arm64 hardware

• The Automox agent running as SYSTEM, since remediation writes to HKLM, loads user hives, and calls online DISM servicing

• Outbound HTTPS access to slack.com so the Worklet can download the architecture-matched MSIX from the Slack desktop release endpoint

• Awareness that Slack closes during the migration and does not reopen on its own, so schedule the run outside a critical shift or let users relaunch it afterward

• No variables to set: architecture detection, profile discovery, and package selection all happen at runtime

Expected Slack state after the migration

Legacy Slack is gone from the endpoint. The machine-wide MSI, every per-user MSI, and every per-user Squirrel install under AppData are removed, along with their Start Menu folders, desktop shortcuts, and uninstall registry entries. The provisioned Slack MSIX is registered on the machine, and the Activity Log records the removed installs and the provisioned package version.

Each user receives Slack at their next sign-in, which is how provisioned MSIX packages register. A user who was signed in during the migration finds Slack closed and can relaunch it once their profile picks up the package. Where the MSIX was already provisioned, the Worklet removes the legacy installs and skips the download rather than reinstalling on top of itself. Re-running evaluation afterward reports the endpoint compliant.