Troubleshooting WinCC WebNavigator Error 8004620f Download

1. Problem Overview

When downloading a WinCC V7.4 SP1 project to a WebNavigator client, the downloader halts indefinitely on the step "Opening WinCC project". The two redundant WinCC servers and the standard WinCC client download without issues; only the WebNavigator client stops responding. After force-clearing .dc cache files in the WinCC project folder, the next download attempt fails outright with the message "An error occurred while changing the computer name in project". The WinCC\diagnose folder subsequently logs the WinCC runtime error code 8004620f.

This symptom chain is well-documented in distributed WinCC V7 / PCS 7 environments and is typically caused by a mismatch between the computer names referenced inside the WinCC project database and the actual NetBIOS / Windows hostname of the WebNavigator client receiving the download. The failure can also be triggered by a corrupted .dc project cache, stale SQL-based redundancy files, or a missing server-side project authorization.

2. Environment Architecture

The reported topology consists of four nodes:

1. WinCC Server #1 – preferred master, holds the project master.
2. WinCC Server #2 – standby server, receives project via redundancy.
3. WinCC Standard Client – single-station client, downloads cleanly.
4. WebNavigator Client – downloads project locally but never completes activation.

3. Symptom Timeline

The fault presents in three observable stages. Each stage reveals an additional layer of the underlying issue.

3.1 Stage A – Permanent Hang at "Opening WinCC project"

The WinCC Explorer Server-Data > Web Navigator Client download dialog progresses through:

1. Establish connection to target computer
2. Stop WinCC Runtime on target
3. Opening WinCC project <HANG>
4. Transferring project files
5. Registering server / Starting Runtime

The process stalls indefinitely (CPU on the WebNavigator client pinned by CCProjectMgr.exe). The WinCC project file <Project>.MCF is opened locally but the SQL Server instance never finishes mounting the runtime database.

3.2 Stage B – Computer Name Change Error

After manual removal of all *.dc files from the project folder, the next download attempt returns a modal dialog: "An error occurred while changing the computer name in project". WinCC's internal computer-name remapping routine fails because the project still references the original NetBIOS name, and SQL Server refuses the rename due to the missing/empty CC_AlgRt.dc and CC_Rt.dc cache files.

3.3 Stage C – Logged Runtime Error 8004620f

The WinCC diagnostic output files report the error code 8004620f. The WinCC diagnostic tool (WinCC\diagnose\Diagnose.exe) lists this code under Runtime > Project management with the long-text "Computer name assignment failed".

4. Root Cause Analysis

Error 8004620f is a WinCC project-management error generated when the runtime cannot resolve the local computer name against the entries stored in the ComputerName table of the WinCC project database (CC_RtAlg_<date>.dat cache, mirrored into *.dc files). In a WebNavigator client scenario the following root causes are observed in production environments:

4.1 Computer-Name / Domain Mismatch

The WebNavigator client host name entered in WinCC Explorer does not match the actual Windows ComputerName or the FQDN used during SQL Server login. WinCC performs a case-insensitive but DNS-aware comparison during project activation; a trailing FQDN suffix or domain rename invalidates the match.

4.2 Corrupt .dc Project Cache

.dc files (CC_Rt.dc, CC_AlgRt.dc, CC_RtAlg.dc, CC_CS.dc) mirror the runtime project database on disk. Forcefully deleting them without a coordinated project re-load corrupts the SQL mirror, leaving the loader unable to read the ComputerName records.

4.3 SQL Server Service Account Privileges

The MSSQLSERVER service on the WebNavigator client (the local runtime instance started by the WinCC Client RT) must run under an account with permission to read/write the WinCC_Project database. If the service runs as LocalSystem while the WinCC project was created under a domain user, the activation of the new computer name fails with 8004620f.

4.4 Missing WebNavigator Client Authorization / License

The WebNavigator Server checks the license and project authorization of the downloading client. If the WebNav.cfg file does not contain the target client's licensed tags, WinCC rejects the download at project-open time, which can manifest as the same hang.

4.5 Distributed System – Computer List Inconsistency

When the WebNavigator client is configured as part of a WinCC distributed system (multi-client OS project), the entry under Computer > Properties > Computer Name must equal the Windows hostname. PCS 7 / WinCC changes the computer name in the project database via the WinCC Explorer > Server Data > Computer context menu. If a previous operator renamed the PC without propagating the rename into the project, the next full download fails.

5. Pre-Fix Diagnostic Procedure

1. Capture the WinCC diag log. Open Start > SIMATIC > WinCC > WinCC Diagnose on the WebNavigator client. Export the latest *.log entries and the APLog from \<computer>\diagnose. Search for 8004620f.
2. Inspect Windows Event Viewer. Filter Application and System logs for the timeframe of the failed download. Look for MSSQLSERVER error 18054, 916, or 17204 indicating database attach failures.
3. Validate the project computer name. In WinCC Explorer on the server, right-click the WebNavigator client under Web Navigator > Client > Properties. Compare Computer name with the actual Windows hostname returned by hostname on the client.
4. Verify SQL Server connectivity. On the WebNavigator client, start SQL Server Management Studio, connect to \<localhost>\WinCC, and confirm the project database is attached and marked (Recovery Pending) or (Suspect) – both indicate a stale .dc mirror.
5. Check service account. Run sc qc MSSQLSERVER. Confirm the START_NAME matches the account used when the project was created on the server.
6. Inspect WebNav.cfg on the server. The file lives in the project folder. Confirm the client entry is present and not commented out.

6. Step-by-Step Resolution

Apply the following remediation in the order listed. Each step includes the Verification action that proves the step succeeded.

6.1 Step 1 – Synchronize the Computer Name

1. On the WebNavigator client, open System > About > Computer Name and note the Full computer name.
2. On the WinCC server, launch WinCC Explorer and select Web Navigator > Client > [client name] > Properties.
3. Update the Computer Name field to exactly match the Windows hostname (case insensitive, no FQDN suffix).
4. Save, close WinCC Explorer, and recompile the server OS via WinCC Explorer > OS > Compile / Check.

Verification: Re-open the client properties – the value persists after Explorer restart.

6.2 Step 2 – Restore the .dc Project Cache

Instead of deleting *.dc files, use the documented Project Duplicator workflow:

1. On the server, launch Start > SIMATIC > WinCC > Project Duplicator.
2. Select the WebNavigator client project, set the target path to the client's \<client>\<project> directory.
3. Tick Replace computer name and enter the client's actual hostname.
4. Click Duplicate. The duplicator regenerates valid .dc, .ldf, and .mdf files atomically.

Verification: The new project folder contains CC_Rt.dc with a recent timestamp and a non-zero file size.

6.3 Step 3 – Reset SQL Server and Re-attach Project DB

1. On the WebNavigator client, stop the WinCC Client RT and the MSSQLSERVER service.
2. Delete the local SQL data folder content for the project (e.g. C:\SQL\<project>) only if the project was originally created on a different machine and the duplication failed.
3. Restart MSSQLSERVER. Run Start > SIMATIC > WinCC > WinCC Project Migrator if the database schema version is older.
4. Open the project with WinCC Explorer – the project must open without prompting for a license-restricted computer name change.

Verification: WinCC Explorer shows Activated under Computer > Status within 60 seconds.

6.4 Step 4 – Validate WinCC/WebNavigator License & Authorization

1. On the WebNavigator Server, open WebConfigurator via http://<server>/WebNavigator.
2. Navigate to Administration > User Administrator and confirm the client has a valid WebNavigator license pool assigned.
3. Open Start > SIMATIC > WinCC > License Analysis & Management and verify that the WebNavigator Client RT license is installed on the client.
4. If the license is missing, install the WinCC WebNavigator Client license via Automation License Manager and re-attempt the download.

Verification: The license report lists Web Navigator Client with status Valid.

6.5 Step 5 – Re-perform the WebNavigator Client Download

1. On the WinCC server, in WinCC Explorer select Web Navigator > Client.
2. Right-click the affected client > Download.
3. Monitor the dialog; the step "Opening WinCC project" should complete in < 30 seconds.
4. After the download completes, WinCC automatically starts the WebNavigator Client runtime.

Verification: The client's WebNavigator Viewer connects to the server and displays the configured start screen.

7. Computer-Name Synchronization Deep Dive

Error 8004620f is intimately tied to WinCC's internal computer-name registry, stored in the table dbo.ComputerName of the runtime database. The table contains three relevant columns:

During download, WinCC executes the stored procedure SP_UpdateComputerName. If the WHERE ComputerName = @NewName clause matches zero rows – typically because the WebNavigator client entry still references a stale hostname – the procedure raises error 8004620f and aborts the transaction. The downloader interprets this as a hang because no further dialog messages are surfaced to the operator console.

The fix is to populate the ComputerName row before initiating the download, which is what WinCC Explorer normally does during the Open Project step. When the .dc cache is empty, that step cannot execute, hence the original hang.

8. WebNavigator-Specific Considerations

The WebNavigator plug-in lives on the server in <WinCC install>\WebNavigator\Server\Web\Install\Custom and is published via IIS. When the WebNavigator client downloads the plug-in to its local cache (%ProgramFiles%\Siemens\Automation\WinCC\WebNavigator\Client\bin), it must match the language pack installed on both server and client.

The client installation procedure requires a clean uninstall + reboot sequence when migrating from a previously failed download. The recommended sequence is:

1. Uninstall SIMATIC WinCC WebNavigator Client via Control Panel.
2. Delete the folder %ProgramFiles%\Siemens\Automation\WinCC\WebNavigator if it survives the uninstaller.
3. Reboot.
4. Re-install via the server's Web Navigator > Install WebNavigator Client download dialog or the manual installer located on the server installation media.

9. Diagnostic Reference – WinCC V7.4 SP1 Error Codes

10. Verification Checklist

• WebNavigator client computer name matches WinCC Explorer entry.
• .dc cache files exist and have valid timestamps.
• MSSQLSERVER service account matches the original project creator.
• WebNavigator Client license is installed and valid.
• Download completes within 60 seconds without hanging at "Opening WinCC project".
• WinCC diagnose log contains no 8004620f after the new download.
• WebNavigator Viewer displays the runtime start picture successfully.

11. Prevention & Best Practices

• Always set the Windows computer name before creating the WinCC project; renaming after the fact forces the operator to run Project Duplicator.
• Never manually delete *.dc files from a WinCC project folder – use Project Duplicator or the WinCC Project Backup workflow.
• Maintain identical language packs on every WebNavigator Server and Client in the distributed system.
• Document the SQL Server service account in the project Computer Properties dialog so future migrations preserve the credentials.
• Schedule periodic WinCC License Analysis to detect expiring WebNavigator Client licenses before they cause download failures.
• When renaming a WebNavigator client PC, always update the name in WinCC Explorer first, recompile, and then perform the Windows rename.

12. Related Siemens References

• Siemens FAQ 33123686 – Which settings should you check if OS loading fails with PCS 7 or the OS project cannot be activated?
• Notes on WebNavigator Installation – TIA Portal Readme
• Installing the WebNavigator Client (RT Professional)