Resolving WinCC OPC Server Error 0x80040154 REGDB_E_CLASSNOTREG in SIMATIC PCS 7

In SIMATIC PCS 7 and WinCC, the COM exception 0x80040154 (REGDB_E_CLASSNOTREG - Class Not Registered) occurs when an OPC client attempts to instantiate a 32-bit WinCC OPC COM object from a 64-bit process without an out-of-process surrogate, or when the OPC Foundation Core Components or WinCC OPC Server registry keys are missing or uninstalled. To resolve it, configure 32-bit execution mode (x86) in the client application, install the 32-bit and 64-bit OPC Core Components redistributable, and verify WinCC OPC Server component registration using regsvr32.

Root Causes of REGDB_E_CLASSNOTREG (0x80040154) in WinCC OPC Architectures

The Windows COM error code 0x80040154 (REGDB_E_CLASSNOTREG) translates formally to Class not registered. In SIMATIC WinCC V7.x and PCS 7 OS stations, this exception is thrown during the initial COM connection call (CoCreateInstance or CoCreateInstanceEx) when an external client application attempts to access the WinCC OPC Server (OPCServer.WinCC, OPCServer.WinCC.A&E, or OPCServer.WinCC.HDA).

The failure is caused by three primary architectural factors:
1. Process Bitness Mismatch (64-bit Client vs. 32-bit WinCC COM Servers): WinCC V7.0 through V7.4 and PCS 7 OS run as 32-bit applications. Their registered in-process COM libraries and out-of-process local servers reside in the 32-bit Windows registry hive (HKEY_CLASSES_ROOT\WOW6432Node\CLSID). If a custom .NET OPC client or third-party historian client is compiled as a 64-bit process (x64 or Any CPU with Prefer 32-bit unchecked on a 64-bit Windows OS), the 64-bit client searches HKEY_CLASSES_ROOT\CLSID. Because the 64-bit registry lacks the requested Class ID (CLSID), Windows returns 0x80040154.
2. Missing or Corrupted OPC Foundation Core Components: WinCC relies on standard OPC Foundation redistributable assemblies (e.g., opcproxy.dll, opccomn_ps.dll). If these core files are damaged, uninstalled by third-party software, or not registered during installation, COM activation fails.
3. Unregistered WinCC OPC Server Binaries: When WinCC updates or updates to PCS 7 are applied without administrative rights, or if an OS project is moved across computers with different paths, the WinCC OPC server DLLs and executables lose their COM class registrations.

32-Bit vs. 64-Bit Registry Architecture Comparison Table

Understanding how COM registration differs between 32-bit and 64-bit subsystems is vital for diagnosing connection errors:

Parameter / Layer32-Bit Client Application64-Bit Client ApplicationNative WinCC V7 / PCS 7 OS ServerRegistry CLSID HiveHKLM\Software\Classes\WOW6432Node\CLSIDHKLM\Software\Classes\CLSIDRegistered in WOW6432Node (32-bit native)System File PathC:\Windows\SysWOW64\C:\Windows\System32\Installed in C:\Program Files (x86)\...DCOM Configuration Toolcomexp.msc or mmc comexp.msc /32comexp.msc (Standard 64-bit MMC)Must be configured via 32-bit MMC viewIn-Process DLL LoadingDirectly compatible with WinCC DLLsFails immediately with 0x80040154Provides 32-bit in-process interfacesOut-of-Process EXE ActivationDirectly connects via standard COMRequires DCOM cross-bitness marshallingWinCCExplorer.exe acts as local server

Distributor and integration advisory: Validate OPC client software entitlements and third-party interface compatibility against authorized vendor specifications.

Step-by-Step Resolution: OPC Core Components and DLL Registration

Execute the following administrative steps on the WinCC station to resolve class registration failures:

Reinstall OPC Foundation Core Components:
* Navigate to the PCS 7 installation media: ...\Support\OPC_Core_Components\.
* Alternatively, download the latest official OPC Core Components Redistributable (x86 and x64) from the OPC Foundation repository.
* Run the installer as Administrator. Ensure both the 32-bit and 64-bit versions are installed on 64-bit Windows systems.
Re-register WinCC OPC COM Components:
* Open an elevated Command Prompt (Run as Administrator).
* Navigate to the WinCC binary directory:
cmd cd /d "C:\Program Files (x86)\Siemens\WinCC\bin"
* Register the core WinCC OPC server binaries:
cmd regsvr32.exe opcda.dll regsvr32.exe opcae.dll regsvr32.exe opchda.dll sopcsrvr.exe /regserver
* Ensure each regsvr32 execution returns a confirmation dialog stating: DllRegisterServer succeeded.
Re-register System COM Marshalling Proxies:
* In the elevated Command Prompt, execute:
cmd cd /d "C:\Windows\SysWOW64" regsvr32.exe opccomn_ps.dll regsvr32.exe opcproxy.dll

Configuring DCOM and Client Process Bitness for WinCC OPC DA/HDA/AE

If the OPC client is an external program developed in C#, VB.NET, or C++:
1. Force 32-Bit Target Platform in Client Application:
* In the Visual Studio or compiler project settings, open Build Properties.
* Change Platform Target from Any CPU or x64 to x86.
* Recompile the executable. This forces the Windows OS to launch the client inside the WOW64 subsystem, directly exposing the 32-bit WinCC COM registrations.
2. Configure 32-Bit DCOM Settings (comexp.msc /32):
* Press Windows Key + R, type mmc comexp.msc /32 and press Enter.
* Navigate to Component Services > Computers > My Computer > DCOM Config.
* Locate OPCServer.WinCC (and OPCServer.WinCC.A&E).
* Right-click and select Properties.
* Under the Security tab, verify that SYSTEM, SIMATIC HMI, and the connecting user account have Launch and Activation Permissions and Access Permissions set to Allow.
* Under the Identity tab, ensure the server runs under The interactive user or a dedicated administrator service account member of SIMATIC HMI.

Verification

Verify that class registration is fully restored:
1. Launch the standard Siemens diagnostic tool OPC Scout V10 or a lightweight third-party tool like OPC Quick Client.
2. Browse local COM servers under OPC DA > Local Server.
3. Confirm that OPCServer.WinCC appears in the list and can be expanded without throwing 0x80040154.
4. Connect to the server, add a test item (e.g., @CPU_RT), and confirm that the item state displays Good with live timestamp updates.

Limitations and Operational Precautions

Never attempt to register 64-bit wrapper DLLs directly over native 32-bit WinCC server DLLs using standard System32\regsvr32.exe; this can corrupt the Windows COM surrogate architecture.
WinCC OPC DA (Data Access) utilizes legacy COM/DCOM technology; for modern, firewall-friendly, cross-network communication, deploy SIMATIC NET OPC UA or the OpenPCS 7 OPC UA interface.
Always ensure the user account running the remote OPC client is configured with matching credentials in the local Windows users group SIMATIC HMI on the WinCC OS server.

Engineer FAQ

Can a 64-bit OPC client connect to a 32-bit WinCC OPC DA server?

Not directly via in-process COM DLLs. A 64-bit client requires an out-of-process DCOM connection, an OPC wrapper/bridge (such as OPC .NET DA wrapper), or the client application must be compiled targeting x86.

What is the difference between error 0x80040154 and 0x80080005?

Error 0x80040154 (REGDB_E_CLASSNOTREG) indicates the server class is not registered in the registry. Error 0x80080005 (CO_E_SERVER_EXEC_FAILURE) means the class is registered, but the executable failed to start or timed out during launch.

Does OpenPCS 7 eliminate the need for 32-bit DCOM configuration?

Yes. OpenPCS 7 provides an OPC UA server interface (IEC 62541), which uses TCP/IP binary communication and bypasses Windows COM/DCOM registry requirements entirely.