Resolving Windows Reboot Loops During Microsoft SQL Server 2014 SP2 Installation in SIMATIC PCS 7 V9.0

During SIMATIC PCS 7 V9.0 installation on Windows 10 or Windows 7, setup loops continuously at the 'SQL Server 2014 SP2 - (WinCC)' step, repeatedly prompting for a system restart without progressing. This occurs when unreleased Windows 10 feature builds (such as semi-annual consumer updates) are used, or when the Windows registry key PendingFileRenameOperations remains populated by third-party update services. To resolve this, verify that the host runs a Siemens-released operating system (e.g., Windows 10 Enterprise 2015 LTSB 64-bit), clear the PendingFileRenameOperations registry value, verify that installation paths contain no spaces or special characters, and manually extract and install the SQL Server setup support packages (sqlsupport.msi).

Root Causes of SQL Server 2014 SP2 Setup Reboot Loops

When installing SIMATIC PCS 7 V9.0, the master setup wizard orchestrates the sequential deployment of system prerequisites, Microsoft SQL Server 2014 Standard Edition SP2 (WinCC instance), Automation License Manager, and WinCC components. A frequent installation blocker occurs when the setup abruptly halts during the SQL Server 2014 SP2 phase with the prompt: 'Please restart your computer before continuing the installation'. After rebooting, re-launching the installer returns immediately to the exact same restart prompt, creating an infinite reboot loop.

This failure is driven by two primary factors:
1. Registry Reboot Flags: Windows maintains session manager registry entries to track pending file replacements scheduled by Windows Update, antivirus scanners, or hardware drivers. If these flags fail to clear, the Microsoft SQL Server bootstrap check halts.
2. OS Incompatibility: PCS 7 V9.0 initial release strictly requires Microsoft Windows 10 Enterprise 2015 LTSB (Long Term Servicing Branch) 64-bit or Windows 7 Enterprise SP1 64-bit. Attempting installation on unreleased Windows 10 consumer channels (e.g., Pro Creators Edition v1703, v1809, or v1903) causes internal Microsoft installer schema mismatches.

Operating System Compatibility: Windows 10 LTSB vs Unreleased Consumer Builds

Siemens industrial automation software relies on standardized Windows kernel interfaces validated through extensive regression testing. Consumer and commercial editions of Windows 10 (Home, Pro, and Enterprise Semi-Annual Channel) receive rolling feature updates that alter underlying DCOM, RPC, and .NET security frameworks. These rolling updates frequently break Microsoft SQL Server 2014 SP2 instance registration.

For SIMATIC PCS 7 V9.0, Siemens explicitly released:
- Windows 10 Enterprise 2015 LTSB 64-bit (Build 10240)
- Windows 7 Enterprise / Ultimate SP1 64-bit
- Windows Server 2012 R2 Standard Edition 64-bit

While some engineers attempt workarounds on non-approved Windows 10 builds (e.g. v1703 or v1809), SQL Server 2014 SP2 frequently fails to create the required WinCC instance services, leading to catastrophic runtime failures later during OS project creation.

Clearing the Windows PendingFileRenameOperations Registry Lock

If the host operating system meets Siemens compatibility requirements but remains trapped in the reboot loop, the PendingFileRenameOperations registry key is the culprit. To clear this lock:

Press Win + R, type regedit, and press Enter to open the Windows Registry Editor with administrator privileges.
Navigate to the following path:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager
In the right-hand details pane, locate the multi-string value named PendingFileRenameOperations.
Right-click PendingFileRenameOperations and select Delete (or rename it to PendingFileRenameOperations_Backup).
Also inspect:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update\RebootRequired
If the RebootRequired key exists, delete it.
Immediately launch the PCS 7 V9.0 Setup without restarting the PC (restarting may cause Windows to re-create the key).

Manual Extraction and Installation of SQL Server 2014 SP2 Support Files

If the SQL Server installer still fails to execute properly after clearing registry flags, the SQL setup support binaries can be installed manually from an elevated command prompt:

Open an elevated Command Prompt (cmd.exe as Administrator).
Create temporary directories on drive C: mkdir C:\sql_x64.
Locate the SQL Server 2014 SP2 executable on the PCS 7 V9.0 DVD or installation media:
SQLServer2014SP2-KB3171021-x64-ENU.exe
Extract the setup files into the directory:
C:\> SQLServer2014SP2-KB3171021-x64-ENU.exe /x:C:\sql_x64
Navigate into the extracted setup directory and execute the support MSI installer:
msiexec /i C:\sql_x64\1033_enu_lp\x64\setup\sqlsupport_msi\sqlsupport.msi /qn
Verify that SQL Server Setup Support Files appears in Windows Programs and Features.
Restart the primary PCS 7 V9.0 master installer.

Diagnostic Matrix: SQL Server Setup Errors and Recovery Procedures

Use the following matrix to identify specific SQL Server bootstrap installation failures:

Error Symptom / Log OutputUnderlying Root CauseDefinitive Engineering RemedySetup loops at reboot promptPendingFileRenameOperations lockedDelete registry key under Control\Session Manager and run setup immediatelyRule 'Reboot required' failedWindows Update pending service rebootClear RebootRequired subkey and disable Windows Update service temporarilyError 1603 during sqlsupport.msiPath contains spaces or special charactersMove media to C:\PCS7_Setup\ without spaces; use local admin account'Instance name WinCC already exists'Corrupt remnants of previous WinCC setupUninstall orphan SQL instances via Control Panel; clean registry keysSetup fails on Windows 10 v1809/v1903Unsupported Windows 10 semi-annual buildRe-image workstation using approved Windows 10 Enterprise 2015 LTSB 64-bitSQL Engine service fails to startGroup Policy blocks 'Log on as a service'Grant NT SERVICE\MSSQL$WINCC rights in secpol.msc -> User Rights Assignment

Verification

Confirm successful resolution and installation of the SQL Server instance:

Open services.msc and verify that SQL Server (WINCC) is present and configured with Startup Type 'Automatic'.
Open SQL Server 2014 Configuration Manager, navigate to SQL Server Network Configuration -> Protocols for WINCC, and confirm that Shared Memory, Named Pipes, and TCP/IP are Enabled.
In the Windows file system, inspect %ProgramFiles%\Microsoft SQL Server\120\Setup Bootstrap\Log\Summary.txt and confirm that the overall installation result reports Passed with 0 failures.
Resume the PCS 7 V9.0 master installer to complete the deployment of WinCC and Engineering tools without further interruption.

Limitations and Operational Precautions

Adhere to the following installation precautions:

Never Use Windows 10 Home or Unreleased Builds: Industrial runtime environments require deterministic servicing branches. Never attempt to deploy production PCS 7 stations on Windows 10 Home or unapproved consumer feature builds.
Registry Backup Precaution: Always export a registry key backup prior to deleting PendingFileRenameOperations.
Avoid Network Share Installation: Always copy installation media to a local SSD drive (e.g., C:\Install\) rather than executing setup across high-latency mapped network drives.

Engineer FAQ

Why does the PendingFileRenameOperations registry key keep returning after I delete it?

If background processes—such as Windows Update, antivirus live scanners, or hardware driver update utilities—are actively downloading or staging patches, Windows continuously regenerates the key. Disconnect the station from the internet, disable the Windows Update service temporarily in services.msc, delete the registry value, and launch setup.

Where can I find the detailed error logs when SQL Server 2014 SP2 setup fails?

Microsoft SQL Server records granular logs in %ProgramFiles%\Microsoft SQL Server\120\Setup Bootstrap\Log. Open Summary.txt for a high-level status report, and inspect the specific subfolder timestamped to your failed installation attempt for Detail.txt and error logs.

Can I upgrade SQL Server 2014 SP2 to SP3 independently on a PCS 7 V9.0 station?

Only if explicitly released in the Siemens Compatibility Tool for your specific PCS 7 version. Installing unreleased Microsoft SQL service packs or cumulative updates can invalidate WinCC database compatibility and break PCS 7 OS project compilation.