WinCC 7.3 to 7.4 Migration: Fix Server, DCF, and MCP Errors

WinCC 7.3 to 7.4 Migration: Resolving Server, DCF, and MCP Errors

WinCC V7.3 to V7.4 migration is documented by Siemens as a direct-open conversion path (no Project Migrator is required for projects that originated in V7.2 or later). Despite this, field engineers routinely encounter six recurring failure modes: the project being reset and reopened as a Standard project, post-migration "Server not connect" messages, the Project Migrator aborting at step 6 or 7, .dcf database configuration corruption, MCP file name mismatch, and SQL Server communication faults. This reference consolidates the verified resolution procedures, file-level diagnostics, and verification checks required to complete the migration cleanly.

1. WinCC V7.x Migration Architecture Overview

Siemens HMI software has used three distinct migration tool generations across the V7 line. Understanding which path applies determines which tool to launch and which exit codes to expect.

The Direct-Open mechanism is implemented inside WinCC Explorer. When a V7.3 project is opened in V7.4 Explorer, the database schema upgrade runs inline, the .dcf file is regenerated, and the project is upgraded in place. There is no separate Migrator executable to invoke. Errors that surface during Direct-Open are functionally identical to errors that used to surface during Migrator-driven upgrade of older projects.

2. Pre-Migration Preconditions

Each precondition below has caused one or more of the documented failure modes. Treat this as a commissioning checklist before launching WinCC Explorer on the V7.3 source.

2.1 Operating System and SQL Server Compatibility

• WinCC V7.4 supports Windows 7 SP1 (64-bit), Windows Server 2008 R2 SP1, Windows 8.1, Windows Server 2012 R2, Windows 10 (1607+), and Windows Server 2016.
• SQL Server must be 2014 SP1 minimum for WinCC V7.4 (installed by SIMATIC WinCC V7.4 setup as SQL Server 2014 SP1 instance).
• If the V7.3 host runs SQL Server 2008/R2, V7.4 must be installed on a clean OS image or alongside with explicit SQL instance separation.

2.2 WinCC Runtime State

The runtime must be deactivated before WinCC Explorer is closed. A background CCWriteHost.exe, CCArchiveSync.exe, or CCAlgRt.exe holding an open handle to ProjectName.mdf will produce a Migrator-style abort if the project is reopened for conversion. Always verify with:

sc query "CCWriteHost"
sc query "CCArchiveSync"
sc query "CCAlgRt"

Each service must report STOPPED prior to V7.4 conversion.

2.3 File-System and Folder Lock Validation

Run Sysinternals handle.exe or Process Explorer against the project directory to confirm no WinCC process holds an open handle:

Any match must be cleared by stopping the owning service before proceeding.

3. Project Structure and File Roles

Diagnostic procedures in this article reference the following project files. All paths are relative to C:\WinCCProjects\<ProjectName>\ unless otherwise stated.

4. Error Class 1: "Project Is Reset and Open As Standard Project"

4.1 Symptom

On launching WinCCExplorer.exe against a V7.3 project from V7.4, the system displays:

The project opens in the Explorer tree but tags, graphics, and archive configuration appear empty. Closing and reopening the project repeats the message and the same reset state.

4.2 Root Cause

The <ProjectName>.dcf file (Database Configuration File) is bound to the V7.3 SQL instance and database identifiers. When V7.4 attempts the inline schema upgrade, the .dcf mismatch causes Explorer to fall back to a default configuration, dropping all custom tag and archive links. The recovery path is to delete the corrupted .dcf so Explorer regenerates it on the next open against the V7.4 SQL instance.

4.3 Resolution Procedure

1. Close WinCC Explorer on the V7.4 host.
2. Confirm all WinCC services are stopped: sc query WinCC must return STOPPED.
3. Open File Explorer and navigate to C:\WinCCProjects\<ProjectName>\.
4. Locate and delete <ProjectName>.dcf.
5. Launch WinCC V7.4 Explorer.
6. Open the project. Explorer regenerates <ProjectName>.dcf bound to the local V7.4 SQL instance.
7. Verify the tag count in Computer → Tag Management matches the V7.3 source.

4.4 Verification

Tag count parity can be checked with a small VBS export from the V7.3 source (before deletion) versus the V7.4 result:

Dim objTagSet
Set objTagSet = HMIRuntime.Tags.CreateTagSet
objTagSet.Add "\\<Server>\TagCountCheck"
MsgBox objTagSet.Item(1).Value

The tag count retrieved in V7.3 must equal the count retrieved in V7.4 within ±0.

5. Error Class 2: "Server Not Connect" After Migration

5.1 Symptom

After conversion completes and the project is reopened, WinCC runtime generates repeated alarms in the diagnostics window:

Connection to server "<ServerName>" interrupted
Server not connect (error 0x80072EE2)

5.2 Root Cause

For server-client or distributed multi-user projects, the V7.3 server package stored under ServerData\ retains V7.3 client version checksums. V7.4 clients reject the V7.3 package and cannot establish the OPC / WinCC Channel connection. Both the server .dcf and the server package must be regenerated.

5.3 Resolution Procedure

1. Open the migrated V7.4 project in WinCC Explorer on the server.
2. Stop the runtime: Server → Runtime → Stop, or net stop "CCAlgRt".
3. Delete <ProjectName>.dcf from the project directory (as in Section 4).
4. Open the project to regenerate .dcf.
5. Navigate to Server Data in Explorer.
6. Right-click the existing client entry and select Delete package.
7. Right-click and select Create server package. Confirm output: ServerData\<ClientName>_<ServerName>.pck.
8. On each V7.4 client, import the new package: WinCC Explorer → Server Data → Import package.

5.4 Server-Client Topology Reference

5.5 Verification

Start runtime on the server, then each client. On the server GDiagnostics window verify Server-Client connection: established for each client. Inspect C:\ProgramData\Siemens\Automation\WinCC\<ProjectName>\Logs\<date>_SC.log for the line Package handshake OK.

6. Error Class 3: Project Migrator Stops at Step 6 or 7

6.1 Symptom

Even though V7.3 → V7.4 is documented as a Direct-Open conversion, engineers sometimes launch the legacy CCMigrator.exe from the WinCC installation directory. The Migrator dialog reports progression through steps 1 through 5, then halts at step 6 (Runtime Database Upgrade) or step 7 (Graphics System Upgrade) with:

6.2 Root Cause

The source V7.3 project was closed while the runtime was still active. A residual WinCC RT process retained an exclusive lock on <ProjectName>.mdf or on a temp file under GraCS\Temp\. The Migrator cannot acquire the lock and aborts.

6.3 Resolution Procedure

1. Re-open the original V7.3 project in V7.3 WinCC Explorer (do not use V7.4).
2. Right-click on the project root → Deactivate project. Wait for the runtime indicator to clear.
3. Verify no WinCC processes remain: tasklist | findstr /i "CCWinCC RT".
4. Close WinCC Explorer. Confirm the file-system handle is released.
5. Copy the entire project directory to a backup location.
6. Open the project in V7.4 Explorer (Direct-Open conversion will run).

6.4 Verification

After successful conversion, navigate to the project root in Explorer and inspect <ProjectName>.log. The closing line must be:

If the line is missing or reads [ERROR] Migration aborted at step 7, repeat Section 6.3 from step 1.

7. Error Class 4: DCF File Corruption (Deep Diagnosis)

7.1 Symptom

The .dcf error frequently co-occurs with Errors 1, 2, and 3. The .dcf is the single most fragile file in the conversion path because it embeds both the SQL Server instance name and the WinCC project database GUID.

7.2 DCF File Structure

If the V7.4 host is configured with a custom SQL instance name (other than WINCC), the .dcf generated by V7.4 Explorer must match. Inspect after regeneration:

The expected return is SQLInstance=WINCC (or the configured custom instance).

7.3 Resolution Procedure (Extended)

1. Stop all WinCC services on the V7.4 host.
2. Back up the existing .dcf: copy <ProjectName>.dcf <ProjectName>.dcf.v73bak.
3. Delete <ProjectName>.dcf.
4. Verify the V7.4 SQL instance is running: sc query MSSQL$WINCC.
5. Open the project in V7.4 Explorer. The .dcf is recreated on first open.
6. Compare the new .dcf with the backup: fc /B <ProjectName>.dcf <ProjectName>.dcf.v73bak.

Any difference in SQLInstance or DatabaseID is expected. Differences in Connection indicate a mismatched encryption seed and must be corrected by re-running the migration.

8. Error Class 5: MCP File Name Mismatch

8.1 Symptom

Opening the V7.3 project in V7.4 generates the message:

8.2 Root Cause

The V7.3 project was renamed at the file-system level (e.g., rename Plant01.MCP Plant01_v2.MCP) without using the WinCC Explorer Project Duplicator. Explorer relies on the MCP file name matching the directory name and matching the entries inside the MCP binary. A direct rename causes Explorer to treat the project as foreign and abort the migration.

8.3 Resolution Procedure

1. Restore the original MCP name if possible (must match the directory name).
2. If a rename is required, use Project Duplicator: Start → SIMATIC → WinCC → Project Duplicator.
3. In the Duplicator dialog, set Source project path and Target project path. Confirm the target directory and target MCP file share the same name.
4. Complete the duplication; verify TargetDir\<NewName>.MCP exists.
5. Open the duplicated project in V7.3 Explorer, deactivate, and close.
6. Open the duplicated project in V7.4 Explorer.

8.4 Naming Rules

• MCP file name = Directory name.
• MCP file name ≤ 24 characters (legacy V6 limitation; V7 tolerates longer but Project Duplicator enforces 24).
• No spaces in MCP file name (Explorer allows but AS-OS engineering tools may not).
• No special characters: & % $ # ! \ / : * ? " < > | ~ ^.

9. Error Class 6: SQL Server Communication Errors

9.1 Symptom

During runtime startup after migration:

Or during project open in Explorer:

9.2 Root Cause

The V7.3 SQL user accounts and database ownership were not carried over to the V7.4 SQL instance. V7.4 installs a fresh SQL Server 2014 SP1 instance named WINCC with fresh security principals. The V7.3 database owner WinCCUser and the WinCCAdmin group must be recreated.

9.3 Resolution Procedure

1. Open SQL Server Management Studio on the V7.4 host.
2. Connect to localhost\WINCC with Windows Authentication.
3. Security → Logins → New Login → WinCCUser.
4. Set Server Roles: dbcreator, processadmin.
5. Set User Mapping for the migrated project database: db_owner.
6. Repeat for the SIMATIC HMI VIEWER and SIMATIC HMI CSP SQL logins if used.
7. Restart the MSSQL$WINCC service: net stop "MSSQL$WINCC" && net start "MSSQL$WINCC".

9.4 SQL Login Reference

10. Step-by-Step Verified Conversion Procedure

The complete, field-proven procedure consolidates all error resolutions into a single ordered workflow.

10.1 Phase A — Backup and Preconditions

1. Archive the V7.3 project: robocopy "C:\WinCCProjects\Plant01" "D:\Backup\Plant01_v73" /MIR /Z.
2. Confirm OS and SQL Server compatibility (Section 2.1).
3. Stop runtime on V7.3 host; deactivate project; close WinCC Explorer.
4. Validate no residual process: tasklist | findstr /i "CC" must return no CCAlgRt or CCWriteHost entries.

10.2 Phase B — Transfer

1. Copy Plant01\ from V7.3 host to V7.4 host at C:\WinCCProjects\Plant01\.
2. Verify file integrity: certutil -hashfile Plant01.MCP SHA256 and compare hashes between source and target.
3. Confirm the MCP file name matches the directory name.

10.3 Phase C — Direct-Open Conversion

1. Launch WinCC V7.4 Explorer on the V7.4 host.
2. File → Open → C:\WinCCProjects\Plant01\Plant01.MCP.
3. Wait for the conversion dialog to complete all phases (typically 60–300 seconds for medium-sized projects).
4. Inspect Plant01.log for Migration completed successfully.

10.4 Phase D — DCF and Server-Client Repair

1. Stop all WinCC services: net stop "CCAlgRt" "CCWriteHost" "CCArchiveSync".
2. Delete Plant01.dcf.
3. Re-open the project in V7.4 Explorer; confirm the new .dcf appears.
4. For server-client: regenerate server package (Section 5.3).

10.5 Phase E — SQL and Permissions

1. Recreate WinCCUser and confirm WinCCAdmin membership (Section 9.3).
2. Verify SQL Server Browser is running: sc query SQLBrowser.
3. Confirm Named Pipes and TCP/IP are enabled in SQL Server Configuration Manager.

10.6 Phase F — Runtime Verification

1. Start runtime: Server → Runtime → Start (or net start CCAlgRt).
2. Open GDiagnostics (Alt+F4 inside runtime, or C:\Program Files (x86)\Siemens\Automation\WinCC\bin\GDiagnostics.exe).
3. Confirm zero entries in Errors and Warnings tabs.
4. Trigger a test tag write from a connected PLC and observe value change in a graphic.
5. Trigger a test alarm and confirm it appears in the Alarm Logging view.
6. Verify archive write: enable an archive, let runtime write one cycle, query the SQL archive table:

11. Migration Diagnostic Matrix

12. Prevention and Best Practices

12.1 Pre-Migration Backup

Always retain a write-blocked V7.3 backup. A read-only backup cannot be modified by V7.4 Explorer on accidental double-click and guarantees a rollback path. Apply the read-only attribute with:

12.2 Project Duplicator for Renames

Never rename MCP files at the OS level. Always use Project Duplicator to preserve internal references.

12.3 Service Account Consistency

Maintain the same Windows service account for WinCC runtime between V7.3 and V7.4 hosts. Mismatched accounts cause SQL ownership gaps.

12.4 Migration Window

Schedule migrations during a process shutdown. Runtime state cannot be deactivated mid-process without tag logging gaps.

12.5 Parallel Migration Testing

Before migrating the production project, migrate a test copy with the same V7.3 build. Validate the entire workflow including server packages, OPC DA/AE, WebNavigator, and Process Historian integration.

12.6 Reference Documentation

• Siemens support entry on V6.2 SP3 → V8.1 upgrade covers the underlying migration framework and is applicable as background reference for V7.3 → V7.4: Migration of WinCC Projects from V6.2 SP3 to V8.1 (PDF).
• TIA Portal migration documentation covering WinCC project lifecycles: Migration (WinCC flexible) - TIA Portal.
• WinCC V7.4 documentation index on the Siemens support portal: Siemens Industry Online Support.

13. Frequently Asked Questions