Resolving OS Compilation Error (302:309): 'Server Data Unable to be Created' in SIMATIC PCS 7

In SIMATIC PCS 7, OS compilation error '(302:309) Server data unable to be created' occurs during the 'Transfer AS/OS Connection Data' phase when WinCC cannot generate or overwrite the server package file (<ProjectName>.pck). This is typically caused by an open WinCC Runtime session locking database files, a locked or corrupted .pck file in the OS project's Packages folder, mismatched computer names between the OS project properties and the Windows OS hostname, or insufficient Windows user group privileges in SIMATIC HMI and SQLServer2005MSSQLUser$Computer$WINCC. Closing WinCC, deleting obsolete .pck files, and verifying the local computer name resolves the error.

Mechanics of Server Data Package Generation in PCS 7 Multiprojects

In a SIMATIC PCS 7 client-server architecture, OS Clients do not access AS automation controllers directly. Instead, OS Clients query OS Servers. To enable this, the Engineering Station compiles connection data and generates a Server Data Package (.pck file) in the OS Server project's Packages folder.

The server data package contains structured metadata, including tag prefixes, alarm message classes, archive tags, and server network endpoints (IP addresses and symbolic computer names). When the OS compilation process runs, the AS-OS Engineering tool invokes internal WinCC APIs (CCServerData.exe or WinCC OLE interfaces) to assemble and write this .pck package. If this creation process is interrupted or blocked, the compilation halts abruptly with the fatal error dialog compile OS (302:309) Error: server data unable to be created.

Root Causes of Error 302:309 During OS Compilation

Field diagnostics across PCS 7 V8.0, V8.1 SP1, and V8.2 identify four primary root causes for error 302:309:

File Locking by Active WinCC Processes: If the target OS project is currently active in WinCC Runtime, or if background processes (such as CCProjectMgr.exe, CCDataServer.exe, or SQL Server service instances) hold open file handles in the OS folder, the compiler cannot overwrite the existing .pck file.
Computer Name Mismatch: In SIMATIC Manager, the WinCC project stores the engineering computer's hostname under WinCC Explorer > Computer. If the physical Windows computer name was changed after project creation, or if the project was retrieved from another engineering laptop, the compiler tries to bind to the old hostname and fails.
Windows Security and DCOM Rights: The active Windows user must be an explicit member of the local Windows groups SIMATIC HMI, SIMATIC NET, and Administrators. Lack of permissions prevents writing to the SQL database tables.
Corrupted Package File: A previously interrupted compile can leave a zero-byte or corrupted .pck file that cannot be parsed or rewritten.

Computer Name Verification and Windows Security Group Rights

To ensure the system environment allows package generation:

Check Computer Name: Open WinCC Explorer directly on the ES for the target OS project. Navigate to the Computer editor. Verify that the configured computer name matches the local Windows environment hostname (run hostname in PowerShell). If it does not match, double-click the computer object, click Change to local computer name, save, and restart WinCC Explorer.
Verify User Group Memberships: Open Windows Computer Management > Local Users and Groups > Groups. Ensure the logged-on engineering account is a member of:
- Administrators
- SIMATIC HMI
- SIMATIC NET
- SQLServer2005MSSQLUser$<Host>$WINCC (or corresponding SQL Server instance group in newer PCS 7 versions).

Step-by-Step Resolution and Package Recreation Procedure

Follow this sequence to eliminate error 302:309 and compile server data cleanly:

Close All Engineering and Runtime Tools: Exit WinCC Runtime on the ES/Server. Close WinCC Explorer and SIMATIC Manager.
Terminate Hanging WinCC Processes: Open Windows Task Manager (or run CCCleaner.exe from the Siemens WinCC bin folder) to ensure all CC*.exe and gsc*.exe processes are terminated.
Clear Obsolete Server Packages: In Windows File Explorer, browse to the OS project directory:
<ProjectPath>\<OS_Folder>\Packages\
Delete any existing .pck files (e.g., OS_Server_1.pck). The compiler will generate a fresh package.
Reset WinCC Project State: Open the WinCC project directly in WinCC Explorer. Verify that the project opens cleanly and that SQL Server connects without database context errors.
Recompile OS from SIMATIC Manager: Launch SIMATIC Manager. Right-click the OS object, select Compile, choose 'Entire OS' (with 'Scope: Entire project'), and ensure 'Generate Server Data' is selected. Click Compile.

OS Compilation Error Diagnostic Matrix

The following table categorizes OS compilation errors related to server data generation and database transfer:

Error CodeReported MessageUnderlying Failure MechanismPrimary Corrective Action302:309Server data unable to be createdTarget .pck file locked or computer name mismatchedRun CCCleaner, delete old .pck, verify local hostname in WinCC302:301Internal error in the compilation phaseSQL Server database locked or disk space exhaustedFree disk space on OS drive; verify SQL Server service is RUNNING302:312No connection to the ASS7 connection undefined in NetPro or missing in HW ConfigOpen NetPro; configure named S7 Connection between AS and OS258:1Database context does not existWindows network share permissions or Simatic Shell unconfiguredConfigure Simatic Shell Terminal Bus adapter and network credentials302:305Driver generator returned warningsUnassigned symbolic addresses or missing module driversRecompile CFC charts with 'Generate Module Drivers' before OS compile

Verification

Confirm successful resolution through the following steps:

Execute the OS compilation in SIMATIC Manager. Confirm that the compilation finishes with '0 Errors' in the compile log.
Navigate to <ProjectPath>\<OS_Folder>\Packages\. Verify that a new .pck file exists with the current system timestamp and a file size greater than 10 KB.
In WinCC Explorer on the OS Client, expand Server Data. Confirm that the newly compiled package appears with the correct server prefix and updated timestamp.
Verify that OS Clients can successfully download or load the package and display process tags from the OS Server.

Limitations and Operational Precautions

Consider these operational constraints when generating server data:

Never Delete the Packages Directory Itself: Only delete the .pck files inside the Packages folder; deleting the folder structure itself can cause directory path exceptions during compile.
Client Package Assignment: In a multi-client project, after compiling server data on the OS Server, you must update the package assignment on all OS Clients (Server Data > Implicit Update or Load Package) before downloading to clients.
Redundant Server Pairs: In redundant OS Server configurations, server data is generated for the master OS and automatically references both redundant server nodes. Ensure both servers have identical symbolic connection names in NetPro.

Engineer FAQ

Where can I find the detailed log file for OS compilation errors?

Detailed logs are stored in <OS_Project_Directory>\Siemens\WinCC\Diagnostics\ and in the SIMATIC Manager compilation log viewer (Options > Logs).

Does changing the Windows computer name require updating the OS project?

Yes. If the PC name changes, you must open WinCC Explorer, update the computer name to the new local hostname under the Computer editor, and restart the station.

How do OS Clients know which redundant OS Server to connect to?

The server data package registers both server names and their IP addresses. WinCC Redundancy on the client automatically arbitrates connection failover between the pair.