Resolving SQL Server Reboot Loops and Windows Compatibility Failures During SIMATIC PCS 7 Installation

Repeated prompts stating 'The system will be rebooted' during the Microsoft SQL Server 2008 R2 (WinCC) installation phase of SIMATIC PCS 7 v8.1 are caused by latched Windows 'PendingFileRenameOperations' registry keys or attempting installation on unapproved operating system releases such as 'Windows 7 Integral Edition'. To resolve this, remove the 'PendingFileRenameOperations' value in the Windows Registry to break the reboot loop, and ensure the host machine runs an officially released edition of Windows 7 (Professional SP1, Enterprise, or Ultimate 64-bit) with approved multi-core processor settings.

Mechanism of the Setup Reboot Loop in PCS 7

During the setup of SIMATIC PCS 7 v8.1, the master installation wizard sequentially installs system prerequisites, Microsoft SQL Server 2008 R2 SP2, STEP 7, and WinCC.

Between sub-installations, the installer queries the Windows operating system to determine whether a restart is pending:
* When third-party drivers, Windows Updates, or previous setup attempts stage file replacements for the next reboot, Windows writes file paths to the PendingFileRenameOperations registry string.
* When the SQL Server or PCS 7 setup detects this registry key populated, it halts and displays: 'Please reboot before installing any more programs' or initiates an automatic reboot.
* If a driver continuously rewrites this key upon startup, the installer enters an infinite reboot loop.

Clearing the PendingFileRenameOperations Registry Key

To manually clear the pending flag and allow installation to proceed:

[Windows Registry Editor (regedit)]
   │
   ├─► Press: Windows Key + R -> Type: regedit -> Press Enter
   │
   ├─► Navigate to Path:
   │     HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager
   │
   ├─► In the Right Pane, Locate:
   │     • Value Name: "PendingFileRenameOperations"
   │
   ├─► Right-click "PendingFileRenameOperations" -> Select: Delete
   │     (Or double-click and clear all text content inside the string)
   │
   └─► DO NOT REBOOT -> Immediately re-launch the PCS 7 Setup.exe installer!

Launching the setup immediately prevents background Windows services from regenerating the pending key.

Operating System Edition Requirements - The Integral Edition Pitfall

A critical cause of catastrophic SQL Server setup failures is attempting to install PCS 7 on customized, stripped, or "Integral" editions of Windows:

Windows 7 EditionReleased for PCS 7 v8.1?System ResultWindows 7 Professional SP1 (64-bit)YES (Fully Released)Supported for ES and OS Client workstations.Windows 7 Ultimate / Enterprise SP1 (64-bit)YES (Fully Released)Supported for ES, OS Single Station, OS Client.Windows 7 Home / Starter EditionNO (Unsupported)Setup terminates; missing IIS and security APIs.Windows 7 'Integral' / Custom ISONO (STRICTLY PROHIBITED)Fails during SQL setup; missing core DCOM/MSMQ libraries.Windows Server 2008 R2 SP1 StandardYES (Fully Released)Required for OS Servers and Process Historian.

Third-party customized ISO images (such as "Integral Edition") remove essential Windows services (e.g. Message Queuing, Performance Counters, Event Tracing) to save disk space. Microsoft SQL Server requires these services; without them, the SQL setup bootstrap crashes.

Multi-Core CPU Affinity During Microsoft SQL Server Installation

On high-performance engineering workstations equipped with modern multi-core processors (e.g. 8 to 16 cores), SQL Server 2008 R2 setup can hang or abort due to a known Microsoft concurrency timing bug during setup bootstrap.

If SQL Server setup fails repeatedly on multi-core PCs:
1. Open Task Manager during the initial phase of setup.exe.
2. Locate the SQL Server setup process (setup100.exe or scenarioengine.exe).
3. Right-click the process -> Set Affinity -> Deselect all cores except CPU 0 and CPU 1.
4. Once the SQL database instances are created, full multi-core processing resumes normally.

Verification

To confirm that the installation has succeeded:
1. Re-run PCS 7 Setup; verify that it progresses past the SQL Server 2008 R2 installation stage without triggering the reboot dialog.
2. In the Windows Services management console (services.msc), verify that the service SQL Server (WINCC) is installed, running, and set to Automatic startup.
3. Review the SQL setup bootstrap log located in C:\Program Files (x86)\Microsoft SQL Server\100\Setup Bootstrap\Log\summary.txt; confirm that all components report Passed.
4. Open SIMATIC Manager and WinCC Explorer; confirm that fresh projects can be created and opened without database connection errors.

Limitations and Operational Precautions

Never modify registry values outside Session Manager\PendingFileRenameOperations. Editing unverified registry keys can corrupt the Windows installation. Always ensure that the operating system installation media is an authentic, unmodified Microsoft OEM or Volume License image adhering strictly to the official Siemens PCS 7 PC Configuration Manual specifications.

Engineer FAQ

Where can I find the exact setup log when SQL Server fails?

SQL Server logs are located under C:\Program Files (x86)\Microsoft SQL Server\100\Setup Bootstrap\Log. Inspect Summary.txt and Detail.txt for specific error codes.

Why did the reboot loop return after I restarted the PC?

If another software installer or hardware driver is malfunctioning, it may re-create the PendingFileRenameOperations key upon every startup. Delete the key and launch the PCS 7 installer without rebooting.

Can I install PCS 7 v8.1 on Windows 10?

No. PCS 7 v8.1 is officially certified for Windows 7 SP1 (64-bit) and Windows Server 2008 R2 SP1. Windows 10 support was introduced starting in SIMATIC PCS 7 v8.2 and v9.0.

Does Microsoft .NET Framework version affect SQL Server installation?

Yes. Microsoft SQL Server 2008 R2 requires Microsoft .NET Framework 3.5 SP1. Ensure .NET 3.5 is enabled under Windows Features prior to launching PCS 7 setup.