Resolving SIMATIC NET V6.3 Configuration Console Fatal Error

Problem Overview

When launching the SIMATIC NET Configuration Console on a workstation running SIMATIC NET PC Software Edition 2005 (V6.3) in combination with STEP 7 V5.3 SP3, the application terminates immediately with the dialog:

Fatal Error
Could not get the interface of the configuration server.

The Configuration Console is the central administrative UI used to bind PC stations, configure OPC server instances, and set S7DOS / S7-REDCONNECT routing parameters via the Configuration Server Windows service (SIMATIC NET Configuration Server). A failure to acquire the COM/DCOM interface handle means the UI cannot reach the in-process COM object hosted by that service, and the console exits before any configuration view loads.

The defect is not hardware-bound. It appears on Field PGs, standard desktops, and on virtual machines alike, and is most frequently reported on Windows XP SP2 with the Data Execution Prevention (DEP) option set to the more aggressive "OptOut" policy that shipped as default in many OEM images.

Affected Software Versions and Environment

The base release of SIMATIC NET 2005 (V6.3) was the first to ship the new Configuration Console UI. Earlier versions (V6.2, V6.1) used the older SIMATIC NET Configuration MMC snap-in and are not affected by this specific fatal error.

Root Cause Analysis

Four independent root causes have been confirmed in the field, any one of which is sufficient to trigger the fatal error. The Configuration Console logs the exception at HKLM\SOFTWARE\Siemens\SIMATIC_NET\Trace (when verbose tracing is enabled) but normally fails silently. Diagnosis therefore requires elimination rather than direct evidence.

Cause 1 — Data Execution Prevention (DEP) Conflict

Windows XP SP2 introduced hardware-enforced DEP (NX bit) and shipped with an "OptOut" default policy that disables execution on data pages for all processes except those explicitly excluded. The Configuration Console relies on dynamically generated stub code in heap-allocated memory to marshal COM calls into the SIMATIC NET Configuration Server service. When DEP is enabled in OptOut mode and the executable is not on the exclusion list, the stub is faulted with STATUS_ACCESS_VIOLATION (0xC0000005) and the process exits with the generic fatal-error dialog.

To verify, open System Properties → Advanced → Performance Settings → Data Execution Prevention. If the radio button is set to Turn on DEP for all programs and services except those I select and SNCC.exe (the console binary) is not listed, this is the active cause.

Cause 2 — Corrupted or Incomplete Installation

SIMATIC NET relies on approximately 1,800 registry keys across HKLM\SOFTWARE\Siemens, HKCR\CLSID (for COM class registration), and HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall. Partial deinstallation, antivirus quarantine of DLLs, or a power loss during the MSI transaction leaves the COM class table inconsistent. When the console attempts CoCreateInstance(CLSID_SnccConfigServer) the COM runtime returns REGDB_E_CLASSNOTREG (0x80040154), which the UI surfaces as "Could not get the interface of the configuration server".

Cause 3 — XDB File / STEP 7 Configuration Conflict

When STEP 7 (specifically the NCM S7 component) is used to push a PC station configuration, it writes an *.XDB file to %ProgramFiles%\Siemens\Automation\SIMATIC_NET\cfg. If the XDB file is written while the Configuration Server service is running and the service is then restarted out-of-order, the COM interface registration for the in-process handler becomes stale. Restarting the console against the stale registration produces the fatal error. The fix is either to (a) avoid XDB push from STEP 7 and configure exclusively inside the Configuration Console / NCM PC, or (b) restart the SIMATIC NET Configuration Server service after every XDB import.

Cause 4 — Hotfix 1 Not Applied

Siemens released Hotfix 1 for SIMATIC NET CD 2005 to address a class of COM marshalling errors in V6.3 on Windows XP SP2. The hotfix replaces snsvc.dll, sncc.exe, and snccres.dll and re-registers the COM classes. Systems running the unpatched base release are not supported on XP SP2 regardless of other configuration.

Diagnostic Procedure

Run the following checks in order. Each is non-destructive and completes in under 60 seconds.

1. Verify installed SIMATIC NET version. Open Add or Remove Programs (XP) or Programs and Features and confirm the entry shows SIMATIC NET PC Software 2005 with version 6.3.x.x. Click Click here for support information to view the exact build.
2. Check Hotfix 1 presence. In Add or Remove Programs, enable the Show updates checkbox. Look for Hotfix 1 for SIMATIC NET CD ROM PC/Software Edition 2005. If absent, root cause 4 is active.
3. Check DEP policy. As described above. Note current setting; you will compare after the fix.
4. Check Configuration Server service. Run services.msc and confirm SIMATIC NET Configuration Server is Started and Startup type: Automatic. If the service is stopped, attempt a manual start. Error 1067 on manual start indicates a corrupted snsvc.ini in the install directory.
5. Check COM registration. Open a command prompt and run: reg query "HKCR\CLSID" /f "SnccConfigServer" /s. A healthy install returns at least 4 sub-keys (InprocServer32, LocalServer32, ProgID, TypeLib). Missing keys confirm root cause 2.
6. Check XDB timestamp. In %ProgramFiles%\Siemens\Automation\SIMATIC_NET\cfg, look for *.XDB modified within the last 24 hours. If present and the service has not been restarted since, root cause 3 is active.
7. Capture event log. Open eventvwr.msc and review Application and System logs for SNCC or snsvc source errors with event ID 1000 or 7034. DEP violations also log as event ID 1000 with 0xC0000005 in the exception code column.

Resolution Path A — Apply SIMATIC NET Hotfix 1

Hotfix 1 is the mandatory first step on any XP SP2 install. It is delivered as a self-extracting archive and is registered with Siemens as KB entry SIMATIC_NET_CD2005_HF1.

1. Close all SIMATIC applications including STEP 7, NCM, and any open Configuration Console instance.
2. Stop the SIMATIC NET Configuration Server service from services.msc. Setting it to Disabled temporarily is recommended to prevent auto-restart.
3. Download the hotfix from the Siemens Industry Online Support portal (entry ID 16525818) and extract to a local folder, e.g. C:\Temp\SN_HF1\.
4. Run setup.exe as Administrator. The installer prompts for the location of the SIMATIC NET installation; point it to the original install path.
5. Reboot the workstation, even if the installer does not request it. Rebooting forces re-registration of the COM classes on first service start.
6. Re-enable the Configuration Server service and set its startup type back to Automatic.
7. Launch the Configuration Console and verify the fatal error no longer occurs.

Resolution Path B — Resolve DEP and Windows Installer Conflicts

This path addresses the most common cause on brand-new Field PGs. The DEP default on XP SP2 OptOut mode is incompatible with the COM stub generated by SIMATIC NET V6.3, even after Hotfix 1.

1. Open System Properties → Advanced → Performance Settings → Data Execution Prevention.
2. Select Turn on DEP for essential Windows programs and services only. This is the equivalent of OptIn mode and is fully supported by Microsoft for XP SP2 and later.
3. Click Apply. Do not reboot yet.
4. If the application must remain in OptOut mode for unrelated reasons, add the console binary to the exclusion list instead: click Add, navigate to %ProgramFiles%\Siemens\Automation\SIMATIC_NET\bin\SNCC.exe, and add it. The change takes effect after reboot.
5. Reboot the workstation.
6. Verify the Configuration Console launches without the fatal error.

When the Field PG was imaged and Windows Update attempted to install patches during SIMATIC NET setup, the Windows Installer can also leave the COM registration in a half-registered state. To clean this up, run the following from an elevated command prompt:

This re-registers the Windows Installer service and forces a re-scan of all installed MSI packages on next use. Allow 30–60 seconds for the operation to complete silently.

Resolution Path C — Correct XDB / STEP 7 Configuration Workflow

If the fatal error began appearing immediately after a configuration change was pushed from STEP 7 to the PC station, the XDB import has left the Configuration Server in an inconsistent state.

1. Close the Configuration Console.
2. From services.msc, restart the SIMATIC NET Configuration Server service. Wait for the status to return to Started; this typically takes 5–10 seconds.
3. Re-open the Configuration Console and confirm normal operation.

To prevent recurrence, change the configuration workflow so that either STEP 7 / NCM S7 or the Configuration Console is the sole owner of the PC station configuration. Mixing the two leads to intermittent fatal errors that are difficult to reproduce. The recommended pattern on V6.3 systems is:

• Use NCM S7 (inside STEP 7) for PC station configuration when the PC is part of a STEP 7 project hierarchy.
• Use the Configuration Console standalone for OPC / S7DOS-only PCs that are not represented in any STEP 7 project.

Resolution Path D — Clean Reinstallation

When Paths A–C fail, the registry is sufficiently damaged that only a clean OS-level reinstall is reliable. The following sequence has been validated on Field PGs running XP SP2.

1. Back up the STEP 7 project archives from %ProgramFiles%\Siemens\Automation\S7Proj and any custom NCM PC configuration files.
2. From Add or Remove Programs, remove in this exact order: SIMATIC NET PC Software 2005, then STEP 7 V5.3, then S7-PCT if present, then any residual Siemens Automation License Manager entries. Reboot after each removal.
3. Run regedit and delete the keys HKLM\SOFTWARE\Siemens and HKLM\SOFTWARE\Wow6432Node\Siemens (the latter on 64-bit hosts). Back up the registry first.
4. Rename %ProgramFiles%\Siemens to %ProgramFiles%\Siemens.old. Do not delete it until the new install is verified working.
5. Reinstall the operating system from the OEM recovery media, or perform a Windows XP Repair Install from the original CD to refresh the COM and Windows Installer components in place. The latter preserves user data but replaces all system files.
6. Apply Windows XP SP2 (or SP3) and the post-service-pack hotfixes, but disable automatic Windows Update while installing SIMATIC software.
7. Install STEP 7 V5.3, then SP3, then the STEP 7 hotfix collection. Reboot between each.
8. Install NCM PC V5.3 SP3 (bundled with STEP 7).
9. Install SIMATIC NET PC Software V6.3 from the CD. Use Typical install unless the OPC server and S7DOS routing are required, in which case use Custom and enable both components.
10. Apply SIMATIC NET Hotfix 1. Reboot.
11. Restore the SIMATIC NET license using the Automation License Manager from the original license USB stick or floppy.
12. Import the backed-up STEP 7 project archives.
13. Re-import the XDB configuration through NCM S7 (preferred) or the Configuration Console (standalone).

Verification Procedure

After applying any of the resolution paths, perform the following validation steps. Each must succeed for the fix to be considered complete.

1. Launch the Configuration Console. The UI must load within 5 seconds and show the PC Station tree view without the fatal-error dialog.
2. Verify service health. From services.msc, confirm SIMATIC NET Configuration Server is Started and remains Started after closing and reopening the console.
3. Verify COM registration. Run the reg query command from the diagnostic procedure. All four sub-keys must be present.
4. Test configuration read. In the console, expand PC Station → Modules. The current module list must appear (typically IE General, OPC Server, and any installed S7DOS components).
5. Test configuration write. Toggle a non-destructive parameter such as the OPC server's Trace level from 0 to 1, click Apply, then change it back. Both writes must commit without error and survive a service restart.
6. Test client connectivity (optional). From a separate STEP 7 station, perform an Accessible Nodes browse over the configured S7 connection. The PC station must appear in the browse list.

Troubleshooting Matrix

Reference: Key File and Service Locations

Field-Proven Caveats

• The fatal error message text is identical across all four root causes. The COM runtime does not propagate a meaningful HRESULT to the user interface, so do not waste time on a literal interpretation of "interface of the configuration server" — it can mean any failure to bind to the in-process COM handler.
• Antivirus products that perform real-time scanning of %ProgramFiles%\Siemens have been observed to re-quarantine snsvc.dll after Hotfix 1 installation, reproducing the symptom 24–48 hours later. Add the SIMATIC NET install directory to the AV exclusion list as part of the fix.
• Do not attempt to install Hotfix 1 over a SIMATIC NET V6.4 or later install. The hotfix is version-specific and will roll back COM registrations.
• On 64-bit Windows (XP x64, Server 2003) the fatal error can also be triggered by WoW64 redirection of the CLSID registry hive. If the install is 64-bit, use the 32-bit registry view (regedit from %windir%\SysWOW64) when verifying class registrations.
• Registry cleanup utilities such as CCleaner are not a substitute for the Hotfix 1 installation and can in fact make the situation worse by removing benign Siemens COM registration entries. Do not run them as part of the fix.