Reference

Installation Reference

Complete command-line reference for installing, upgrading, repairing, and uninstalling CYNC. Covers all parameters, feature selection, silent/passive modes, and enterprise deployment examples.

CYNC ships as a single Cync.Setup.exe bootstrapper bundle built with WiX v5. It bundles all prerequisites (ASP.NET Core 10 runtime, Windows App Runtime 1.8, VC++ Redistributable) for fully offline installation. The bundle wraps an MSI package that registers the Windows Service and installs the admin dashboard.

For a quick interactive walkthrough, see the Getting Started guide. This page is the full reference.

Install modes

The bootstrapper supports three display modes, controlled by command-line switches:

Mode	Switch	Behavior
Interactive	(none)	Full wizard UI with EULA, feature tree, and installation directory selection.
Passive	/passive	Progress bar only — no wizard, no user prompts. Useful for attended deployments where you want visual feedback without interaction.
Silent	/quiet	Completely silent — no UI at all. Required for SCCM, Intune, and Group Policy deployments.

Tip: In silent and passive modes, the EULA is automatically accepted. You are responsible for ensuring that your organization's deployment process includes EULA acceptance.

Actions

Use these switches to control what the bootstrapper does. If no action switch is specified, the default is /install.

Switch	Description
/install	Install the product (default action).
/uninstall	Uninstall the product. Removes the service, binaries, and shortcuts. The data directory (`%ProgramData%\CYNC`) and database are preserved.
/repair	Repair the installation. Reinstalls missing files and re-registers the service.
/modify	Modify the installation. Opens the feature tree to add or remove the Admin UI.
/layout <dir>	Download all packages to the specified directory for offline redistribution. Does not install.
/norestart	Suppress automatic reboots. If a reboot is required (e.g., after .NET runtime install), it is deferred.

Parameters

Parameters are passed as Name=Value pairs after the action/mode switches. All parameters are optional.

Parameter	Type	Default	Description
InstallService	0 \| 1	1	Install the CYNC sync service (Windows Service). Set to `0` to install the admin dashboard only (e.g., on an admin workstation for remote management).
InstallUI	0 \| 1	1	Install the WinUI 3 admin dashboard. Set to `0` to install the service only (headless/Server Core deployment). On Server Core, the dashboard is automatically excluded regardless of this setting.
EnableRemoteAdmin	0 \| 1	0	Enable the gRPC-over-HTTPS remote administration endpoint. When set to `1`, the installer places an `appsettings.Production.json` overlay that enables the HTTPS endpoint on port 5123 with an auto-generated self-signed certificate. See HTTPS configuration.
InstallFolder	path	C:\Program Files\CYNC\	Override the installation directory. The service installs under `InstallFolder\Service\` and the dashboard under `InstallFolder\UI\`.

Note: Parameter names are case-sensitive. Use the exact casing shown above (e.g., EnableRemoteAdmin=1, not enableremoteadmin=1).

Logging

The bootstrapper writes a detailed log file that is invaluable for troubleshooting installation failures. Use the /log switch to specify a log path:

Cync.Setup.exe /quiet /log "%TEMP%\CyncInstall.log"

If /log is not specified, the bootstrapper writes to %TEMP% with an auto-generated file name.

Feature selection

The MSI contains two top-level features. The interactive installer presents a feature tree; silent/passive installs use the InstallService and InstallUI parameters.

Feature	Contents	Default
CYNC Service	Sync engine, gRPC server, Windows Service registration (`CyncService`), and `%ProgramData%\CYNC` data directory.	Installed
CYNC Admin UI	WinUI 3 administration dashboard, Start Menu shortcut.	Installed(desktop only)
↳ Desktop shortcut	Creates a shortcut on the desktop for the admin dashboard.	Installed

Server Core auto-detection

The installer reads the InstallationType registry value from HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion. If the value is Server Core, the admin dashboard feature and its UI prerequisites (Windows App Runtime, VC++ Redistributable) are automatically excluded. No manual configuration is needed.

Prerequisites

The bootstrapper installs the following prerequisites automatically before the MSI. All prerequisites are bundled for offline installation:

Prerequisite	Required for	Skipped if
ASP.NET Core 10 Runtime	Service	Already installed (≥ 10.0.0)
Windows App Runtime 1.8	Admin UI	Server Core, or UI not selected
VC++ Redistributable (x64)	Admin UI	Already installed, Server Core, or UI not selected

Examples

Default silent install (service + dashboard)

Installs both the sync service and the admin dashboard to the default directory.

Cync.Setup.exe /quiet

Service only (headless server)

Installs only the service, with remote admin enabled. Ideal for Server Core or headless VMs.

Cync.Setup.exe /quiet InstallUI=0 EnableRemoteAdmin=1

Dashboard only (admin workstation)

Installs only the admin dashboard for remote management of a CYNC service on another machine. No Windows Service is registered.

Cync.Setup.exe /quiet InstallService=0

Custom install directory

Installs to a custom directory. The path must end with a backslash.

Cync.Setup.exe /quiet InstallFolder="D:\Apps\CYNC\"

Passive install with logging

Shows a progress bar during installation and writes a detailed log.

Cync.Setup.exe /passive /norestart /log "C:\Logs\CyncInstall.log"

Full Server Core deployment

Complete silent install for a headless server: service only, remote admin enabled, custom directory, no restart, with logging.

Cync.Setup.exe /quiet /norestart ^
  InstallUI=0 ^
  EnableRemoteAdmin=1 ^
  InstallFolder="D:\CYNC\" ^
  /log "%TEMP%\CyncInstall.log"

SCCM / Intune / Group Policy deployment

For enterprise software deployment tools, use the silent install with no restart. Check the exit code to determine success.

Cync.Setup.exe /quiet /norestart EnableRemoteAdmin=1

Exit code	Meaning
0	Success
3010	Success, reboot required
1602	User cancelled (interactive only)

Upgrade

CYNC uses the WiX major-upgrade pattern. Running a newer version of Cync.Setup.exe automatically uninstalls the previous version and installs the new one. No manual uninstall is needed.

What is preserved

All configuration stored in the SQLite database (%ProgramData%\CYNC\cync.db)
Sync history and delta tokens
License activation state
Log files
Custom appsettings.Production.json (remote admin configuration)

Silent upgrade

Cync.Setup.exe /quiet /norestart

The same parameters apply. Feature selection and remote admin settings are carried forward from the previous installation unless explicitly overridden.

In-app update

The admin dashboard includes a built-in update checker. Navigate to the About page and click Check for updates. If a new version is available, click Install update to download and install it automatically. The dashboard will close, update, and relaunch.

Uninstall

Interactive

Use Apps & features (Settings → Apps → Installed apps) and search for “CYNC”, then click Uninstall.

Silent

Cync.Setup.exe /uninstall /quiet

What is removed

Service binary and registration
Admin dashboard binary
Start Menu and desktop shortcuts
Firewall rule (if created)

What is preserved

%ProgramData%\CYNC\ — database, logs, certificates
Contacts synced to Exchange Online mailboxes (CYNC does not delete contacts on uninstall)

Clean uninstall: To remove all data after uninstalling, manually delete %ProgramData%\CYNC. To remove synced contacts from mailboxes, delete the CYNC contact folder in each mailbox before uninstalling.

Repair

If the service fails to start due to missing files or a corrupted installation, run a repair:

Cync.Setup.exe /repair /quiet

This reinstalls all binaries and re-registers the Windows Service. Configuration data in %ProgramData%\CYNC is not affected.

Directory layout

After installation, CYNC files are organized as follows:

C:\Program Files\CYNC\
├── Service\              # Sync engine binaries
│   ├── Cync.Service.exe  # Windows Service executable
│   ├── appsettings.json  # Default configuration
│   └── ...               # .NET assemblies
└── UI\                   # Admin dashboard binaries
    ├── Cync.UI.exe       # WinUI 3 dashboard
    ├── Assets\           # Icons and images
    ├── Pages\            # XAML compiled pages
    └── ...               # .NET + WinUI assemblies

%ProgramData%\CYNC\
├── cync.db               # SQLite database (config, sync history, target users)
└── Logs\
    └── cync-2025-01-15.log  # Daily rolling log files

The data directory (%ProgramData%\CYNC) is ACL-hardened to LocalSystem and BUILTIN\Administrators only.

Troubleshooting

Installer reports “newer version already installed”

You are running an older version of the installer than what is currently installed. CYNC does not support downgrades. Uninstall the current version first, then install the desired version.

Service does not start after installation

Check the Windows Event Log (Application) for errors from the CyncService source. Common causes: .NET runtime not installed (use Cync.Setup.exe instead of the MSI directly), or another service using the same named pipe.

Admin dashboard shows “Cannot connect to service”

Verify the service is running: sc query CyncService. If the service is running, ensure the dashboard was launched with administrator privileges (the named pipe is ACL-restricted to Administrators).

Silent install exits with a non-zero code

Use /log to capture the detailed install log and check for prerequisite failures or OS version blocks. The bootstrapper requires Windows build 17763 or later.

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