How to Resolve 'Master Server Is Not Activated' and Restore OS Delta Downloads After ES Ghost Image Recovery

In SIMATIC PCS 7, restoring an Engineering Station (ES) from a disk image (such as Symantec Ghost or Acronis) frequently breaks the ability to perform 'Changes Only' delta downloads to redundant OS Servers, producing the error 'The Master Server is not activated, please perform an entire OS download' even when WinCC Runtime is active. This occurs because the disk image restoration restores stale project GUIDs, orphaned SQL transaction logs, or mismatched Windows security identifiers (SIDs). To resolve this, verify that local Windows user credentials and SIMATIC HMI group memberships match across ES and OS nodes, execute an Entire OS Download once to re-synchronize project GUIDs, and clear lingering database locks with reset_wincc.vbs.

Impact of Disk Image Restoration on SIMATIC Project Integrity

Restoring an Engineering Station from raw sector-based disk images (Norton Ghost, Acronis True Image):
* The Restoration Trap:
* Disk images restore the exact state of the hard drive from when the backup image was created weeks or months prior.
* In the intervening time, the production plant continued operating: redundant OS servers synchronized archives, processed thousands of batch logs, and updated runtime database timestamps.
* When the restored ES attempts a delta download, its internal tracking tables clash with the live OS Server cluster.

Root Causes of 'Master Server Is Not Activated' Delta Download Rejection

When the ES reports 'The Master Server is not activated':
1. Mismatched Project GUIDs:
* Every WinCC project contains a unique Globally Unique Identifier (GUID) generated during project creation.
* If the restored ES has an older GUID or different internal version ID than the live OS Servers, WinCC blocks delta compilation to prevent database corruption.
2. Loss of DCOM and SQL Security Context:
* Creating a new Windows user account on the restored ES creates a new Security Identifier (SID). Even if the username and password match textually, Windows assigns a new internal SID.
* The OS Server rejects incoming DCOM queries from the new SID, preventing the ES from reading the online @RM_MASTER tag state.
3. Cached Standby/Master Confusion:
* The ES cannot query which redundant server is currently Master (@RM_MASTER = 1), defaulting to the assumption that no master is active.

Windows Security Identifier (SID) and User Credential Synchronization

To restore security trust between the restored ES and the OS Servers:

Re-Align User Accounts and Passwords:
* Ensure that the exact same local Windows Administrator username and password exist on ES, Server 1, and Server 2.
* Ensure password is set to Password never expires.
Verify Local Group Memberships:
* On all three machines, add the user account to:
- Administrators
- SIMATIC HMI
- SIMATIC NET
Execute SIMATIC Security Controller:
* On the restored ES, launch SIMATIC Security Controller.
* Click Repeat Settings to re-register DCOM access permissions, firewall rules, and registry keys for the new user profile. Reboot the ES.

Re-Establishing Project GUID Alignment via Entire OS Download

Once security trust is restored, project GUID alignment must be re-established:

Why Entire Download Is Mandatory Once:
* A delta download ('Changes Only') requires existing database schema synchronization.
* Because the restored ES database is desynchronized, an Entire Download must be performed once to re-baseline the servers.
Execution Sequence on Redundant Servers:
* Step A: Deactivate WinCC Runtime on Standby Server (Server 2).
* Step B: From the ES, perform an Entire Download to Server 2: PLC > Download > Entire WinCC Project.
* Step C: Activate WinCC Runtime on Server 2. Confirm it assumes process control.
* Step D: Deactivate WinCC Runtime on Master Server (Server 1).
* Step E: Perform an Entire Download to Server 1 from the ES.
* Step F: Activate WinCC Runtime on Server 1.
Restoring Delta Downloads:
* Once both servers have received the identical master database from the restored ES, make a minor test change in CFC.
* Execute PLC > Download > Changes: delta downloads will now succeed seamlessly without error popups!

Comparison of Disk Image Restoration vs Native PCS 7 Archiving

The table below compares recovery mechanisms for PCS 7 Engineering Stations.

Recovery MethodRestores Software Installation?Preserves Live Project Synchronization?Risk of Database LockRaw Disk Image (Ghost / Acronis)Yes (Full OS & Applications)NO (Stale GUIDs & SIDs)High (Requires Entire Download)Native Multi-Project Archive (.zip)No (Requires installed software)Yes (Pure engineering database)LowSIMATIC Version TrailNoYes (Version controlled)MinimalClean OS Reinstall + Project RetrieveYesYesZero

Verification

To confirm that OS delta downloads are restored:
1. In SIMATIC Manager on the restored ES, verify that both redundant OS servers can be pinged by hostname.
2. Open WinCC Explorer on the ES: compile OS (Compile OS > Changes Only).
3. Select Target OS > PLC > Download > Changes.
4. Confirm that the download dialog executes through all delta steps without displaying 'Master Server is not activated'.
5. On the active Master OS Server, verify that WinCC message journal logs: Delta download successfully completed.

Limitations and Operational Precautions

Never restore an Engineering Station from an unverified disk image directly to a live production plant during critical manufacturing phases; schedule restoration during a planned maintenance window.
When executing Entire Downloads to redundant servers, always update one server at a time to prevent complete loss of operator plant visualization.
Before taking raw disk images of an Engineering Station, always run reset_wincc.vbs to ensure SQL databases are closed and consistent.
Always validate final software licensing, backup procedures, and system security settings against the applicable Siemens catalog and authorized distributor quotation.

Engineer FAQ

Why did delta download say 'Master Server not activated' when it clearly was running?

The restored ES could not authenticate via DCOM to the server's WinCC process manager due to a new Windows SID, preventing the ES from reading the online @RM_MASTER status.

Will performing an Entire Download lose my plant's historical trend data?

Historical archives reside on the active server's hard drive. Performing an Entire Download overwrites project configuration files (.mcp), but historical SQL archives can be preserved or synchronized from the redundant partner.

Can I avoid Entire Downloads after restoring an ES image?

Only if the disk image was taken recently and the project on the ES was updated with an exact, identical multi-project archive retrieved from the active plant.