Uninstalling WinCC Unified Completely: TIA Portal Cleanup Guide

1. Problem Overview

WinCC Unified Engineering and WinCC Unified PC Runtime are delivered as TIA Portal option packages. Although the TIA Portal Portal main installer exposes a "Repair/Modify/Uninstall" entry in Programs and Features, the WinCC Unified sub-packages, their SQL Server prerequisites, and their Automation License Manager (ALM) components are registered as independent MSI/MSP packages. When a user runs the TIA Portal uninstaller, only the core Portal components are removed; the HMI Unified option package frequently survives because of:

• Independent MSI product codes for SIMATIC WinCC Unified PC and SIMATIC HMI WinCC Unified Engineering that are not chained into the Portal main product tree.
• Microsoft SQL Server instances (e.g., WINCCPLUS, WINCCUNIFIED) registered against the WinCC product and not the Portal product.
• License-server, runtime, and web-server services that are uninstalled at the binary level but leave HKEY_LOCAL_MACHINE\SOFTWARE\Siemens and HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Siemens keys behind.
• Residual folders in %ProgramFiles%\Siemens\Automation, %ProgramFiles(x86)%\Siemens\Automation, and %ProgramData%\Siemens\Automation.
• Scheduled tasks, environment variables (S7RTM, SIMATIC), and ODBC DSNs that the uninstaller skips.

The result is a PC on which Programs and Features still shows SIMATIC WinCC Unified PC V16/V17/V18, SIMATIC HMI WinCC Unified Engineering, and Microsoft SQL Server 201x (64-bit) even after the TIA Portal entry is gone. This blocks the subsequent installation of a different WinCC flavor (e.g., WinCC Professional V15.1, WinCC Comfort/Advanced) because the setup bootstrapper detects conflicting product states and aborts with error 1603 or the dialog "The installation of WinCC has been canceled due to an existing WinCC installation."

2. Identify What Is Actually Installed

Before touching anything, capture a baseline. Run an elevated PowerShell session and dump the installed MSI product codes:

For 64-bit-only visibility (which Programs and Features sometimes hides), use the registry directly:

Get-ItemProperty HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*,
              HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\* |
  Where-Object {$_.DisplayName -match "Siemens|WinCC|Unified|SIMATIC"} |
  Select-Object DisplayName, DisplayVersion, UninstallString | Format-Table -AutoSize

Note any of the following canonical product names (used by Siemens across V16, V17, V18, and V20):

3. Prerequisites

1. Local administrator account. WinCC Unified services (SIMATIC WinCC Unified RT, ScadaServer, UMCRuntimeServiceHost) are protected by the service control manager; only an admin can stop and remove them.
2. Original TIA Portal / WinCC Unified installation media (ISO or downloaded package). The standard Control Panel uninstaller re-launches the bootstrapper that ships with the original setup package and can request source files. If the original media is unavailable, copy the matching setup package to a writable folder first (see Section 5).
3. Siemens Inventory Tool (Siemens Installer Assistant / Inventory.exe). Located at C:\Program Files (x86)\Common Files\Siemens\Automation\Siemens Installer Assistant\407\Inventory.exe. Used by Siemens Support for clean uninstalls. Reference: Siemens KB 76325723 - Inventory Tool for TIA Portal.
4. Microsoft SQL Server Installation Center (already present in Start → Microsoft SQL Server 20xx → SQL Server Installation Center) if a manual SQL instance removal becomes necessary.
5. System restore point. Create a restore point before any registry edits: Checkpoint-Computer -Description "Pre-WinCC-Unified-Removal" -RestorePointType "MODIFY_SETTINGS" (PowerShell) or via System Protection → Create.
6. Backup any HMI project files from %ProgramData%\Siemens\Automation\WinCCUnified\ and %USERPROFILE%\Documents\Siemens\WinCCUnified\. The uninstaller does not preserve them.

4. Method 1 - Standard Programs and Features Removal (Official)

Per the SIMATIC HMI WinCC Unified Engineering V18 installation guide (ID 109813308), the canonical Siemens-documented removal path is the standard Windows Programs and Features workflow.

4.1 Procedure

1. Close TIA Portal, WinCC Unified Engineering, the WinCC Unified Runtime Viewer, and the SIMATIC Automation License Manager. Kill any S7ULPMA.exe, ScadaRts.exe, or CCEServer.exe in Task Manager.
2. Open Control Panel → Programs and Features (or Settings → Apps → Installed apps on Windows 10/11).
3. Order the list by Publisher = Siemens AG and uninstall in the following order:
   1. SIMATIC WinCC Unified Update UPDx (highest patch level first, to avoid file-locked errors).
   2. SIMATIC HMI WinCC Unified Engineering Vxx.
   3. SIMATIC WinCC Unified PC Vxx — this is the runtime host. Per the TIA Portal V20 documentation (Uninstalling WinCC Unified - TIA Portal V20 docs), select "SIMATIC WinCC Update uninstall all desired components of WinCC" in the bootstrapper dialog.
   4. Any remaining SIMATIC WinCC entries that were not part of the original TIA Portal product (Runtime, Configuration, Connectivity Pack).
4. Confirm each uninstaller finishes with "Uninstallation completed successfully." Do not reboot between steps unless the installer explicitly requests it.
5. Reboot when all WinCC Unified entries are gone.

4.2 Resulting State

After a clean run, the registry keys HKLM\SOFTWARE\Siemens\Automation\WinCCUnified and the matching WOW6432Node mirror are deleted, the SIMATIC WinCC UnifiedRT Windows service is removed, and the %ProgramFiles%\Siemens\Automation\WinCCUnified tree is removed. The Microsoft SQL Server instance, however, is intentionally not removed — proceed to Section 7.

5. Method 2 - Bootstrapper Re-Launch (When the Original Entry Is Missing)

If Programs and Features does not list the WinCC Unified package (a common symptom when the bootstrapper cleanup was interrupted by power loss, a third-party uninstaller, or an antivirus quarantine of Siemens.Automation.Runtime.exe), re-run the original setup:

1. Insert or mount the original TIA Portal / WinCC Unified ISO. If you no longer have the ISO, copy the contents of the WinCC Unified installation package (the Setup folder containing Start.exe) to a writable local folder. The path matters: copy to the root of a drive (e.g., D:\TIA_V18_Setup\) to avoid a Setup.exe MAX_PATH problem.
2. Run Start.exe as administrator.
3. When the bootstrapper opens, choose Modify / Repair / Uninstall. If the Modify tree already shows the Unified packages as installed, select them and click Uninstall. The bootstrapper executes the underlying MSI with REMOVE=ALL and re-cleans the registry.
4. For TIA Portal V20 and later, the documentation explicitly states to select "SIMATIC WinCC Update uninstall all desired components of WinCC" — see Uninstalling WinCC Unified (TIA Portal V20 documentation).

6. Method 3 - Siemens Automation License Manager and Installer Assistant

The Siemens Automation License Manager (ALM) hosts the Siemens Installer Assistant which is the recommended cleanup tool per Siemens KB 76325723.

1. Launch the Installer Assistant. Its default location is C:\Program Files (x86)\Common Files\Siemens\Automation\Siemens Installer Assistant\<version>\Siemens.Automation.InstallerAssistant.exe (or Inventory.exe in older versions).
2. Select Installed software. The tool enumerates all Siemens TIA Portal option packages, hotfixes, and runtime components, including those hidden from Programs and Features.
3. Select every WinCC Unified-related entry and click Uninstall. The assistant removes the MSI, dependent services, and the corresponding HKLM\SOFTWARE\Siemens keys in a single transactional pass.
4. Reboot when prompted.

7. Method 4 - Microsoft SQL Server Instance Removal (Mandatory for WinCC Unified)

WinCC Unified stores runtime data, alarms, and the project database in a SQL Server instance. The most common instance names are:

If these instances remain after WinCC Unified is removed, future installations of TIA Portal V15.1, WinCC Professional, or even TIA Portal V18 with a different service pack will fail at the SQL prerequisite check. The official removal procedure is documented at Removing an SQL instance - TIA Portal V20 documentation.

7.1 Standard SQL Instance Removal (Control Panel)

1. Open Control Panel → Programs and Features.
2. Locate every Microsoft SQL Server 201x (64-bit) entry. Each instance registers as a separate product (e.g., Microsoft SQL Server 2017 (64-bit), Microsoft SQL Server 2019 (64-bit)). For each entry whose instance was created by WinCC Unified, click Uninstall/Change.
3. In the SQL Server setup dialog, choose Remove, then select the specific instance (WINCCUNIFIED or WINCCPLUS).
4. Select Database Engine and any related shared features used only by WinCC Unified. Leave common shared features such as SQL Server Browser or SQL Server Management Studio in place unless they are explicitly tied to the instance.
5. Confirm and let the SQL installer run. The instance services (MSSQL$WINCCUNIFIED, SQLAgent$WINCCUNIFIED) and the related registry hive HKLM\SOFTWARE\Microsoft\Microsoft SQL Server\<InstanceId>\ are deleted.

7.2 SQL Instance Removal via SQL Server Configuration Manager

1. Stop the MSSQL$WINCCUNIFIED and SQLAgent$WINCCUNIFIED services.
2. Open the SQL Server Installation Center (SQLServerManager15.msc or via Start Menu) and choose Installation → Remove node from a SQL Server failover cluster or use the command-line uninstaller: setup.exe /Action=Uninstall /FEATURES=SQLENGINE,REPLICATION,AS,RS,IS /INSTANCENAME=WINCCUNIFIED /Q.
3. Reboot. Confirm with: Get-Service | Where-Object {$_.Name -match "WINCCUNIFIED|WINCCPLUS"} — should return nothing.

7.3 Manual SQL Cleanup (Last Resort)

If the standard uninstall fails (e.g., "There is no SQL Server instance that can be uninstalled from this bootstrapper"):

1. Delete the instance data directories: C:\Program Files\Microsoft SQL Server\MSSQL15.WINCCUNIFIED\MSSQL\ and C:\Program Files\Microsoft SQL Server\MSSQL15.WINCCUNIFIED\MSSQL\DATA\.
2. Delete the matching registry hive: HKLM\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL15.WINCCUNIFIED and HKLM\SOFTWARE\WOW6432Node\Microsoft\Microsoft SQL Server\MSSQL15.WINCCUNIFIED.
3. Remove the SQL services: sc.exe delete MSSQL$WINCCUNIFIED and sc.exe delete SQLAgent$WINCCUNIFIED (elevated CMD).
4. Re-run the TIA Portal / WinCC Professional setup. If setup still complains about residual SQL, manually rename HKLM\SOFTWARE\Microsoft\Microsoft SQL Server to .bak, run setup (which will see no SQL), then restore the original key.

8. Method 5 - Service and Scheduled-Task Cleanup

Even after a clean MSI removal, orphaned WinCC Unified services occasionally remain. Verify and remove:

Typical services to expect after a clean state (these should be gone):

• SIMATIC WinCC UnifiedRT (WinCC Unified Runtime Host)
• ScadaServer (data server)
• UMCRuntimeServiceHost (UMC = User Management Component)
• S7RTM (Runtime Manager)
• SIMATIC ALM Service — only remove if ALM is also being uninstalled
• CCEServer (Connectivity Core Engine)

For each orphan, remove it via an elevated command prompt:

sc.exe stop   <ServiceName>
sc.exe delete <ServiceName>

Remove scheduled tasks:

Remove environment variables (these are referenced by older TIA Portal versions):

[Environment]::SetEnvironmentVariable("S7RTM",  $null, "Machine")
[Environment]::SetEnvironmentVariable("SIMATIC", $null, "Machine")

9. Method 6 - File-System Cleanup

After MSI removal, the following directories typically persist and should be removed manually only after verifying they contain no project backups:

10. Method 7 - Registry Cleanup (Advanced, Last Resort)

When the uninstallers all return success but a subsequent TIA Portal V15.1 (or any version below the one that installed Unified) refuses to install with "A newer version of WinCC is installed", the residual product/upgrade registry keys are the cause. The most common offenders are:

• HKLM\SOFTWARE\WOW6432Node\Siemens\Automation\WinCCUnified\<version> — product state, language packs, installed updates list
• HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UpgradeCodes\<GUID> — upgrade suppression flags
• HKLM\SOFTWARE\Classes\Installer\Products\<GUID> — MSI product code that survived
• HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\<GUID> — the Programs and Features entry that survived a partial uninstall

10.1 Targeted Search and Delete

Open regedit as administrator and use Find (F3) to search for these strings. Delete only the matching key, not the parent. Repeat for each:

• WinCCUnified
• SIMATIC HMI WinCC Unified
• SIMATIC WinCC Unified PC
• Siemens.Automation.WinCCUnified
• S7RTM (only in ...\Siemens\ subtrees)

10.2 OLE/COM Cleanup

WinCC Unified installs COM/OPC UA type libraries under HKCR\TypeLib\<GUID>. To find orphaned ones:

1. Open Regedit → HKCR\TypeLib.
2. For each GUID, check whether the win32 subkey points to C:\Program Files\Siemens\...\*.dll that no longer exists. Delete only those with a missing file target.

10.3 UMC User-Management Certificates

The User Management Component (UMC) writes local user records to HKLM\SOFTWARE\Siemens\UserManagement. If a fresh install complains about existing users, delete this subkey after backing it up.

11. Verification Checklist

Run every check. A green result across all rows is required before installing any TIA Portal / WinCC variant.

12. Troubleshooting Matrix

13. Common Errors and Their MSI Exit Codes

14. Reinstallation Validation

After the verification checklist returns all-green, perform a minimal re-install dry run to confirm a clean state:

1. Insert the original TIA Portal / WinCC Unified installation media and start the bootstrapper.
2. The package selection screen should mark the WinCC Unified option as Not installed. If it shows Repair / Modify / Uninstall, the cleanup is incomplete.
3. Install only the WinCC Unified Engineering component with a minimal configuration. Complete the install.
4. Open the engineering tool, create a test project, and confirm the compiler runs without "Database could not be opened" errors. This proves the SQL instance is functional and no orphan keys are blocking it.
5. If everything succeeds, the environment is clean. You may now safely uninstall the test install using Method 1 to return the PC to a bare state, or proceed to install the target WinCC flavor (e.g., WinCC Professional V15.1).

15. Reference Document Map

All official Siemens documentation relevant to this procedure:

• SIMATIC HMI WinCC Unified Engineering V18 - ID 109813308 — installation, modification, and uninstallation via Programs and Features.
• Uninstalling WinCC Unified - TIA Portal V20 documentation — bootstrapper "SIMATIC WinCC Update" uninstall flow.
• Removing an SQL instance - TIA Portal V20 documentation — Microsoft SQL Server instance removal for Unified.
• Siemens KB 76325723 - Inventory Tool for TIA Portal — Installer Assistant cleanup utility.