Troubleshooting WinCC Cannot Open/Create Project XREF Error

The "Cannot open/create WinCC project - Project Manager can't start the basis application XREF" error is a recurring fault on Siemens WinCC 7.x SCADA stations. It appears during project open, project create, and post-update launches, and blocks the entire engineering and runtime pipeline because the WinCC Explorer shell cannot instantiate its core DataStore/TagLogging component. This reference covers every verified root cause, the diagnostic routine, and the corrective steps for SIMATIC WinCC V7.0 through V7.5 environments running on Windows Server 2003, Windows XP, and Windows 7.

1. Problem Statement

The WinCC Explorer displays a modal dialog with the exact text:

Cannot open/create WinCC project - Project Manager can't start the basis application XREF

The error is raised by the WinCC Project Manager (component CCProjectMgr.exe) when it cannot initialize the XREF (Cross Reference) basis application, which is the data engine that links the WinCC project database, the runtime tag container, the alarm logging subsystem, and the user archive. When XREF fails to start, the project graph cannot be built, no tags are loaded, and no picture can be opened.

Symptom fingerprint:

• WinCC Explorer opens but no project is listed in the project tree.
• Clicking Open, New, or selecting a project file (*.mcp) immediately aborts with the XREF message.
• The error persists across reboot, re-installation, and project recreation attempts.
• No WinCC runtime services (WinCCExplorer, CCAlgRtServer, CCDatabaseEngine) appear in Task Manager or stop immediately after start.

2. Affected Products and Versions

The error has been confirmed on the following configuration matrix. Newer versions use a different error set, but the same fault class is captured in CCStorageError.h for TIA Portal / WinCC Professional (RT Professional).

3. Root Cause Analysis

Siemens-internal diagnostic logs and the official Siemens Support entry "Why is the error message 'Open WinCC project' ... displayed?" identify four independent root-cause families. Each one requires a different corrective action.

3.1 Cause A - File Access / Project Corruption

The project file (*.mcp) or one of its sub-databases is still locked by another process, has been moved, or is partially written. Siemens Support article 23712529 states: "One cause of this might be that the file is not available or is defective. This might happen if the project file is still being accessed." Typical triggers:

• Antivirus real-time scan holds an open file handle on *.mcp or *.ldf.
• Backup software (e.g., Veeam, Acronis) is reading the project directory while the user clicks Open.
• The project was copied from a removable drive that is no longer mounted.
• Project was last saved with a newer WinCC SP than the one currently installed (downgrade scenario).

3.2 Cause B - SQL Server (WinCC) Service Failure

WinCC stores runtime data in a Microsoft SQL Server instance named SQL Server WinCC (instance ID CC_WINCC). When this Windows service is stopped, disabled, set to Manual with no logon account, or blocked by UAC, the XREF basis application cannot bind to the data source and the open/create operation aborts. This is the single most common cause on Windows 7 and Server 2008 R2 stations.

3.3 Cause C - Remote Desktop Session Context

When the engineer opens WinCC Explorer from a Remote Desktop (RDP) session, the XREF process inherits the session token from the terminal services client. On Windows Server 2003 / XP, only the console session (session 0) has the required desktop heap and window-station privileges to launch the basis application. A standard RDP session runs in session 1 or higher and fails. The historical mitigation is the /console switch (mstsc /console). After Windows XP SP3, the switch was renamed to /admin:

3.4 Cause D - User Rights and Installation Order

The XREF basis application requires the Windows user account to be a member of the local SIMATIC HMI group and to have Log on as service and Log on as batch job privileges. It also requires that the WinCC installation was performed in the correct sequence with STEP 7 / TIA Portal; reversing the order or installing a newer TIA Portal after WinCC 7.x overwrites shared COM/DCOM entries used by the basis application.

4. Pre-Diagnostic: Gather Information

Before changing any configuration, capture the state of the station. Open an elevated command prompt and run the diagnostic bundle:

1. Locate the WinCC diagnose files:
   C:\Program Files\Siemens\Automation\WinCC\diagnose\ (V7.0 to V7.4)
   C:\Program Files (x86)\Siemens\Automation\WinCC\diagnose\ (32-bit install on 64-bit OS, V7.5)
   Open every *.log file, search for the substring XREF, BasisApplication, or CCProjectMgr.
2. List all WinCC-related Windows services:
   sc query | findstr /i "wincc sql"
3. Verify the SQL Server WinCC instance is reachable:
   osql -E -S \.\CC_WINCC -Q "SELECT @@VERSION" (WinCC < 7.4)
   sqlcmd -S \.\CC_WINCC -E -Q "SELECT @@VERSION" (WinCC >= 7.4)
4. Capture the file lock on the project:
   handle.exe -a "C:\Path\To\Project.mcp" (Sysinternals)
5. Check the local groups:
   net localgroup "SIMATIC HMI"
whoami /groups | findstr /i "simatic"

5. Solution Matrix

6. Solution A - Restore File Access and Project Integrity

1. Open Services (services.msc) and stop all WinCC-related services (WinCC Explorer, WinCC Runtime, WinCC AlarmLogging, SQL Server WinCC).
2. Exclude the project directory and C:\Program Files\Siemens\Automation from real-time antivirus scanning. Add the following to Windows Defender or third-party AV:
   *.mcp; *.ldf; *.mdf; *.bak; *.log; *.snr
3. Verify the project directory is on a local NTFS volume. Network shares and ReFS volumes below Windows Server 2012 are not supported as primary project storage in WinCC 7.x.
4. If the project was created on a newer WinCC version, use the Project Migrator (Start > Siemens Automation > WinCC > Project Migrator) to convert it downward. If the conversion is from a version older than what the current shell can read, you must instead upgrade the installed WinCC - downgrades are not supported.
5. Rebuild the XREF table by opening the project and selecting Project > Cross References > Rebuild. Allow 5-30 minutes for large projects.

7. Solution B - Restore the SQL Server WinCC Service

The "MySQL was switched off" failure pattern, observed on WinCC V7.0 SP3, is resolved entirely by the SQL service restart procedure. Note: the actual product is Microsoft SQL Server, not MySQL; the field terminology is often mis-translated.

1. Open Services (services.msc) as Administrator.
2. Locate SQL Server (WinCC). The display name is SQL Server (WinCC) and the service name is SQL_SERVER_WINCC (WinCC <= 7.0) or MSSQL$CC_WINCC (WinCC >= 7.2 with named instance CC_WINCC).
3. Right-click > Properties > set Startup type to Automatic. Verify the Log On account is NT AUTHORITY\SYSTEM or a dedicated service account with the Log on as service right.
4. Click Start. If the service fails with error 1053, increase the service startup timeout:
   reg add "HKLM\SYSTEM\CurrentControlSet\Control" /v ServicesPipeTimeout /t REG_DWORD /d 120000 /f and reboot.
5. Test connectivity:
   osql -E -S \.\CC_WINCC -Q "SELECT name FROM sysdatabases"
   Expected output lists the WinCC project database matching the project name.
6. Reopen WinCC Explorer. The XREF error should be gone.

8. Solution C - Use the Correct Remote Desktop Session

For engineers who manage the SCADA station from a remote desk, the proper connection depends on the client operating system:

1. Windows XP SP2 client → Server 2003:
   mstsc /v:SERVERNAME /console
2. Windows XP SP3 / Vista / 7 client → Server 2003 / 2008:
   mstsc /v:SERVERNAME /admin
3. Windows 10/11 client → Server 2008 R2 and newer: open Remote Desktop Connection, click Show Options, switch to the Experience tab, then check Connect to an admin session. Equivalently, run:
   mstsc /v:SERVERNAME /admin

Verification: open Task Manager on the server while the RDP session is active. The active session should show Active console = Services, and your session row should be ID 0. If your session ID is 1 or higher, you are not on the console and the XREF error will re-occur.

When RDP cannot be used (VPN packet loss, slow link, locked policy), connect a USB keyboard, USB mouse, and a monitor directly to the server and operate from the local console session. The basis application launches reliably in the local hardware console session because it owns the full window station token.

9. Solution D - Restore User Rights and Installation Order

1. Confirm the engineer is a member of the local groups:
   net localgroup "SIMATIC HMI"
net localgroup "SIMATIC NET" (if Softnet is used)
2. Grant the right to Log on as service and Log on as batch job:
   secpol.msc → Local Policies → User Rights Assignment → Log on as service → add the user or the SIMATIC HMI group.
3. Verify DCOM access for the WinCC components:
   

   dcomcnfg.exe → Component Services → Computers → My Computer → DCOM Config
   Open CCProjectMgr, CCAlgRtServer, CCDatabaseEngine, and CCBaseApXRef → Properties → Security and ensure Everyone or the SIMATIC HMI group has Launch and Activation permissions.

4. If the order of installation was incorrect, follow the Siemens-prescribed order: STEP 7 V5.5 first, then WinCC V7.x, then any TIA Portal V12+. Never install TIA Portal V16+ on a host that still hosts WinCC 7.0; the shared DCOM keys and SQL native client libraries will be overwritten.

10. Error Code Reference

The error message in WinCC V7.x is a user-facing wrapper around a Windows and a SQL error. The map below lets you match the dialog text to the underlying HRESULT and to the documented WinCC Professional (TIA) storage error class.

For the full WinCC Professional (RT Professional) storage error class, see the official CCStorageError.h reference page in the TIA Portal documentation.

11. Verification Procedure

After each fix, run the following acceptance test before returning the station to production:

1. Open WinCC Explorer as the affected user (not as Administrator) and confirm the project tree populates without the XREF dialog.
2. Start WinCC Runtime (Start > WinCC Runtime) and verify in the status bar that the activation phase reaches Running within 30 seconds.
3. Open the Tag Management editor and check that the internal tags @CurrentUser, @CurrentPassword, and @LocalMachineName are present and have valid values.
4. Trigger a test alarm and confirm it is written to the alarm log database on the CC_WINCC SQL instance:

5. Close WinCC Explorer cleanly. Verify the SQL Server WinCC service is still Running and that the project lock file (*.lock) is removed from the project directory.
6. Reboot the server, log in via console (or /admin RDP), and re-run steps 1-5. The error must not reappear.

12. Preventive Maintenance

• Schedule a weekly restart of the SQL Server (WinCC) service to clear temporary locks. Use a scheduled task running net stop "SQL_SERVER_WINCC" && net start "SQL_SERVER_WINCC".
• Add the WinCC project path and Siemens\Automation directory to AV exclusions before commissioning.
• Document the RDP client and target OS pair in the station logbook so that future engineers do not silently break the console session requirement.
• Track WinCC SP and TIA Portal versions in a CMDB. Apply WinCC SPs only on stations whose STEP 7 / TIA Portal version is in the Siemens compatibility matrix.
• Enable crashdump collection for the WinCC processes:
  reg add "HKLM\SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps\CCProjectMgr.exe" /v DumpType /t REG_DWORD /d 2 /f

13. Frequently Asked Questions