Siemens Information Server Cannot Connect to Process Historian After Admin Password Change

This troubleshooting reference documents the failure mode in which a Siemens Information Server (IS) loses its connection to a SIMATIC Process Historian (PH) database immediately after a Windows administrator password rotation on the PH/IS host. The Information Server ConfigurationManager wizard is re-run successfully, the OS server pair reconnects to PCS 7 OS, yet the IS web front end and reporting services still return an authentication or HTTP 500.0 error when querying the PH database. The documented resolution is the synchronization of all SIMATIC Process Historian and Information Server Windows service logon accounts with the new administrator credential.

1. Environment and Component Topology

The failure occurs in a typical PCS 7 V9.x / V10 process-control architecture with the following components, which may be installed on a single redundant OS server pair or split between two physical servers:

The Information Server accesses the PH database through the CCCAPHServer Windows service, which acts as the WCF (Windows Communication Foundation) gateway between the IIS-hosted IS web site and the underlying SQL Server PH instance. Two additional services support PH-IS communication:

• PHREADY – Process Historian readiness service. Validates PH database state on startup and exposes health endpoints.
• PH – Main Process Historian service. Owns the writer/reader queues and feeds the SQL Server PH database.

2. Failure Symptoms

After the Windows administrator password is changed on the OS server pair and the Information Server ConfigurationManager is re-run with the new credential, the following symptoms are observed:

1. The Information Server web portal (http://<server>/InformationServer or https://<server>/InformationServer) returns an HTTP error, typically HTTP 500.0 – Internal Server Error, when any report or dashboard is opened.
2. The PCS 7 OS clients successfully archive to the Process Historian. PH itself is functional and the SQL Server PH database continues to grow.
3. The Information Server ConfigurationManager (InformationServer\ConfigurationManager\ConfigurationManager.exe) reports a successful reconfiguration when re-run with the new administrator password.
4. Windows Event Viewer » Application log shows WCF / SQL connection errors citing "login failed" or "cannot open database requested by the login".
5. Windows Event Viewer » System log shows the CCCAPHServer, PH, or PHREADY services with Event ID 7034 ("service terminated unexpectedly") or Event ID 7000 ("service failed to start due to logon failure").

3. Root Cause Analysis

The Information Server ConfigurationManager updates the following artifacts with the new administrator password:

• The appsettings / connectionStrings of the IS web site configuration.
• The encrypted credential store used by the IS runtime to authenticate against the PH database.
• The SQL Server login mapping for the srvPHAdmin or equivalent IS service principal.

However, the Windows Service Control Manager (SCM) maintains an independent copy of the service "Log On" credentials. The SCM credentials are used by the Windows kernel to start the CCCAPHServer.exe, PHREADY.exe, and PH.exe processes. If the SCM still holds the previous (now invalid) password, the service start fails with Logon failure: unknown user name or bad password (Win32 error 1326) and the IS web portal cannot reach the PH database through the dead WCF endpoint.

Specifically, three independent credential stores must agree:

The standard fix published by Siemens Support and observed in field practice is to update all three credential stores with the new administrator password.

4. Pre-Resolution Checklist

Before modifying service accounts, validate the following:

1. Network reachability – ping <PH-server> from the IS host returns a reply. ICMP is allowed.
2. Domain / workgroup state – Confirm the server has not been moved out of the domain or workgroup. The whoami /all output shows the expected domain prefix or local SID.
3. Name/IP stability – Verify the PH server hostname and IP have not been changed. The IS PHServerName registry value must match.
4. Local admin group – The new administrator account is a member of the local Administrators group on the PH/IS host (net localgroup Administrators).
5. SQL Server state – The SQL Server service is started and the PH database is online (SELECT state_desc FROM sys.databases WHERE name = 'ProcessHistorian').

5. Step-by-Step Resolution

5.1 Re-run Information Server ConfigurationManager

1. On the IS host, log in as the new administrator.
2. Open Information Server ConfigurationManager from C:\Program Files (x86)\SIEMENS\InformationServer\ConfigurationManager\ConfigurationManager.exe.
3. Select Modify Configuration. Enter the new administrator user name and password when prompted.
4. Complete the wizard. The ConfigurationManager rewrites the encrypted IS config, updates the IS web site in IIS, and re-syncs the SQL Server login mapping for the IS service account.
5. Leave the ConfigurationManager open until the SCM update in the next step is complete.

5.2 Update Windows Service Logon Accounts

The CCCAPHServer service alone is not sufficient. All three service logon accounts must be aligned to the new administrator credential. The same principle applies to any additional PH-related services present in the install.

1. Open Services (services.msc) as the new administrator.
2. For each service listed below, double-click, open the Log On tab, and re-enter the new administrator password:
   1. CCCAPHServer – the IS WCF gateway. Must match the ConfigurationManager credential exactly.
   2. PHREADY – Process Historian readiness service. Logon must match the PH service account.
   3. PH – Process Historian core service. Logon must match the PH service account.
   4. (If present) PHDiag, PHDiagnostics, OPC UA Wrapper – align to the same account.
   5. (If SQL Server is co-located) SQL Server (PHINSTANCE) and SQL Server Agent (PHINSTANCE) – align to the same administrator account or a dedicated service account that has been granted sysadmin on the PH database.
3. Click Apply. A confirmation dialog states "The account <DOMAIN\Administrator> has been granted the right to log on as a service". Click OK.
4. Repeat for the standby OS server if you run a redundant PH pair.

5.3 Restart the Service Stack in the Correct Order

Restart the services in dependency order to avoid transient "database not ready" errors. From an elevated command prompt or PowerShell:

net stop "CCCAPHServer"
net stop "PHREADY"
net stop "PH"

REM wait 15 s for SQL Server transactions to settle
timeout /t 15 /nobreak

net start "PH"
net start "PHREADY"
net start "CCCAPHServer"

For a redundant pair, perform the restart on the standby node first, confirm replication catches up, then restart the primary node. Do not restart both nodes simultaneously.

5.4 Restart the IIS Application Pools

The Information Server runs as an IIS web application under the InformationServerAppPool. The pool caches the IS service-account credential for the lifetime of the worker process. Recycle the pool to pick up the new credential:

%windir%\system32\inetsrv\appcmd recycle apppool /apppool.name:"InformationServerAppPool"
iisreset /noforce

After iisreset, wait for the W3SVC service to reach the Running state before testing the portal.

6. Verification and Acceptance Test

Run the following checks in sequence. Each must pass before moving to the next.

6.1 Service Health

sc query "CCCAPHServer" | findstr "STATE"
sc query "PH"         | findstr "STATE"
sc query "PHREADY"    | findstr "STATE"

All three must report RUNNING.

6.2 IS Web Portal Reachability

Open http://<IS-host>/InformationServer in a browser. A successful load shows the Information Server home page with the configured report tree on the left. If the page returns HTTP 500.0, follow the Microsoft IIS guidance to enable detailed errors and Failed Request Tracing:

• Microsoft: HTTP Error 500.0 – Internal Server Error (IIS)

HTTP 500.0 in this context almost always resolves to a credential failure between the InformationServerAppPool identity and the downstream CCCAPHServer WCF endpoint. Confirm the app pool identity and the CCCAPHServer SCM logon use the same account.

6.3 IS-ConfigurationManager Test Connection

Re-open the IS ConfigurationManager and use Test Connection against the Process Historian database. A green status confirms the encrypted config, the SQL login, and the WCF endpoint all agree.

6.4 End-to-End Report Test

Open a representative IS report (e.g. Process Value Archive) and confirm tag data is returned from the PH database. The first query after a restart may take 5–10 s; subsequent queries should be sub-second.

7. HTTP 500.0 Error Deep-Dive

When the IS portal returns HTTP 500.0 – Internal Server Error, the underlying IIS pipeline is signaling that an unhandled exception escaped the ASP.NET application. The Microsoft reference article documents the standard diagnostic procedure:

1. Enable HTTP Error Responses in IIS » ASP » Debugging Properties » Send Errors to Browser = True (development only).
2. Inspect the IIS worker process event log for the ISAPI or HttpHandler exception stack.
3. Enable Failed Request Tracing for status code 500 and review the FREB log.

For the PH-IS scenario, the most common 500.0 root cause is the System.ServiceModel.Security.SecurityNegotiationException raised when the IS web service cannot negotiate a Windows token with the CCCAPHServer. The fix is the SCM logon alignment covered in section 5.2.

8. Service Account Best Practices

The following practices prevent recurrence and simplify future password rotations:

• Dedicated service account. Use a dedicated domain account such as svc-SIMATIC-PH instead of the local Administrator. Grant the account Log on as a service via Group Policy.
• Group Policy preference. Deploy the service-account password as a Group Policy Preference (GPP) scheduled item that updates all SCM logons in one operation. Never store the password in plain text in a script.
• Symmetric credentials on both nodes. The active and standby OS servers must use identical service-account credentials. Document the account name in the plant password vault.
• Pre-rotation test. Rehearse the rotation on the test PH/IS pair. Capture a baseline of: service states, IS portal load time, and a sample report render time. Compare after each production rotation.
• Service dependency review. After each rotation, run sc qc "CCCAPHServer" and confirm the DEPENDENCIES field is unchanged. A missing dependency indicates the install was not pristine.

9. Troubleshooting Matrix

10. Reference Documentation

Official sources used to validate this procedure:

• Siemens Support: Installation of Process Historian and Information Server (Entry ID 66579062)
• Microsoft: HTTP Error 500.0 – Internal Server Error (IIS)