WinCC v7.5 Runtime Blank Screen: GraCS PDL Save Error Fix

WinCC v7.5 Runtime Blank Screen and GraCS PDL Save Failure — Field Troubleshooting Reference

WinCC v7.5 (SIMATIC WinCC, formerly the information-level component of the SIMATIC HMI family) is a 32-bit SCADA runtime and configuration suite for Windows 7 SP1, Windows Server 2008 R2 SP1, Windows 10 (LTSC/Enterprise 2019 where validated), and Windows Server 2016/2019. Two related defects have been observed on unpatched WinCC v7.5 stations: the Graphics Designer cannot save .pdl process pictures back into the project's GraCS folder, and the WinCC Runtime either starts with a blank canvas or hangs in an "endless loading" state when launched from any picture. This article documents root-cause analysis, the official Siemens update channels, folder-level recovery, file-system permission correction, and full project restoration.

1. Problem Summary

The failure has two interacting symptoms:

• Symptom A — Save failure into GraCS: In Graphics Designer, when saving a modified picture the dialog returns "File not found. Check the correctness of the file name and try again." The error appears regardless of whether the picture was opened from GraCS or from a temporary working location.
• Symptom B — Runtime hangs or renders blank: After activating the project, Runtime either stalls in initialization ("RT loading" with no progress, no DLG-Passport entry), or activates successfully but draws an empty canvas. No element is visible even though the picture index contains valid entries.
• Symptom C — Re-save loops: Saving an already-modified .pdl over the original file fails with "Failed to save document." Subsequent edits become unsaveable until WinCC Explorer is restarted.

The defect is reproducible on any .pdl, which rules out picture-level corruption and points to a project-wide runtime / configuration issue.

2. Root Cause Analysis

The most frequently documented trigger is a missing or outdated WinCC v7.5 Service Pack and Update package. WinCC v7.5 was released in early 2018 and superseded by v7.5 SP1 and v7.5 SP2; each Service Pack bundles cumulative defect fixes, signed binaries for the runtime DLLs (PDLRT.dll, HMIRuntime.dll, CCDCore.dll), and updates to CCLicSrv, CCMsgMgr, and the Graphics Designer components. Stations running on the original v7.5 RTM build expose the save-dialog regression and the GD-init hang.

Secondary causes (in descending frequency) include:

Because the user has explicitly stated that no Service Pack or Update is installed for the affected v7.5 station, the unpatched RTM build is the primary suspect. The remaining branches are diagnostic alternatives if a fully patched installation still exhibits the defect.

3. Pre-Upgrade Environment Verification

Capture the following baseline before touching the system so that a rollback is possible.

1. Open Windows Start → winver. Confirm OS build and architecture. WinCC v7.5 is 32-bit and requires the matching 32-bit redistributables.
2. Open WinCC Explorer → Help → About. Record the exact build string (e.g., V7.5.0.0, V7.5.1.0, V7.5.2.0).
3. List installed updates: appwiz.cpl → "View installed updates" and filter for SIMATIC WinCC. Record all KBxxxxxxx entries.
4. Stop the WinCC runtime: WinCC Explorer → RT → Stop. If unresponsive, terminate CCExplorer.exe, PDLRT.exe, HMIRuntime.exe via Task Manager.
5. Back up the project folder entirely, including the GraCS, library, Wscripts, ArchiveManager, Logging, and Common subdirectories. The project root typically lives under C:\Program Files (x86)\Siemens\Automation\WinCC\WinCCProjects\<ProjectName> unless relocated.
6. Export the registry hive HKEY_LOCAL_MACHINE\SOFTWARE\Siemens\WinCC and the user hive HKEY_CURRENT_USER\SOFTWARE\Siemens\WinCC using regedit /e to a timestamped .reg file.

4. Solution Path A — Install the Latest WinCC v7.5 Updates

Siemens ships updates as self-extracting executables that include the Service Pack, individual Hotfixes, and consolidated Update packages. The two principal update entry points for v7.5 are:

4.1 Determine the currently installed Service Pack

1. Open WinCC Explorer and select Help → About → System Information. The dialog lists the WinCC base version (e.g., 7.5.0) and the installed Service Pack / Update.
2. Cross-check via regedit at HKLM\SOFTWARE\Siemens\Automation\WinCC\CurrentVersion. The value ServicePackLevel reports the SP number; the value Build reports the patch level.

4.2 Apply the cumulative update package

1. Download the appropriate self-extracting package from the Siemens Industry Online Support entries above. Sign in with a Siemens Industry account (free registration).
2. Extract the archive to a local folder — never run from a network share or from the project directory.
3. Stop all WinCC services: WinCC Explorer → Stop Runtime, then exit WinCC Explorer. Verify in Task Manager that PDLRT.exe, CCExplorer.exe, HMIRuntime.exe, and CCLicSrv.exe are not running.
4. Launch the setup as Administrator (right-click → Run as administrator). The installer prompts for the installation path; do not change it.
5. During the install, choose Update — install all components of the current installation. Accept the license terms and let the installer replace binaries.
6. Reboot the operator station. Many updates require a restart to load the signed runtime libraries.

4.3 Validate the new build

After reboot:

• WinCC Explorer → Help → About must now display a build string ≥ V7.5.2.x when SP2 was applied.
• The folder C:\Program Files (x86)\Siemens\Automation\WinCC\Bin must contain patched PDLRT.dll, HMIRuntime.dll, and CCDCore.dll with a timestamp matching the update.
• The Start menu must show SIMATIC WinCC → Documentation → Readme updated to the new Service Pack revision.

5. Solution Path B — Restore GraCS Folder Integrity

If the save dialog still rejects files after the update, the GraCS folder itself is corrupted. Use the procedure below to rebuild the directory.

1. Close Graphics Designer and WinCC Explorer.
2. Rename the existing folder from GraCS to GraCS_old_yyyymmdd. The runtime will not start without a valid GraCS folder; the rename is purely diagnostic and can be reverted.
3. Create a fresh GraCS folder in the project root.
4. Copy *.pdl files back from GraCS_old_... in small batches (10–20 files). Attempt to open one in Graphics Designer; if save succeeds, copy the next batch.
5. Locate the orphan *.pdl_cache directories in the original folder. These are derived caches used by the PDL runtime. Delete them — they will be regenerated by the runtime on first activation.
6. Inspect the project master file <Project>.pwx for trailing whitespace or non-ASCII characters in [GraCS] entries. Remove any reference to a picture that no longer exists.

6. Solution Path C — Repair File Permissions and Sharing

Windows ACL misconfiguration is the most common cause of "saves elsewhere, fails in GraCS" behavior.

1. Right-click the project root folder → Properties → Security → Advanced.
2. Confirm CREATOR OWNER has Full Control with the Subfolders and files only scope.
3. Confirm the user account that runs WinCC Explorer (typically the logged-on interactive user, or the dedicated SIMATIC HMI service account) has Modify rights.
4. If the project lives on a UNC path, verify that SMB signing on the server matches the client (WinCC requires consistent signing or explicit disabling in LocalGroupPolicy.msc).
5. Disable real-time antivirus scanning on the project directory, on PDLRT.exe, and on WinCCExplorer.exe. Add the WinCC Bin and project folders to the AV exclusion list.

6.1 Symbolic-link and reparse-point audit

fsutil reparsepoint query "C:\Program Files (x86)\Siemens\Automation\WinCC\WinCCProjects\<Project>\GraCS"
dir /AL "C:\Program Files (x86)\Siemens\Automation\WinCC\WinCCProjects\<Project>\GraCS"

If the output shows a reparse tag (e.g., 0xa0000003 for a symbolic link), the path resolves through a network share. Replace it with a local directory to avoid intermittent save failures.

7. Solution Path D — Clean Reinstallation Procedure

Use this path when multiple updates fail or the WinCC instance is migrated to new hardware.

1. Open Settings → Apps and uninstall SIMATIC WinCC V7.5 plus all SIMATIC WinCC V7.5 SPx entries.
2. Remove leftover folders: C:\Program Files (x86)\Siemens\Automation\WinCC, C:\ProgramData\Siemens\Automation\WinCC, and %AppData%\Siemens\Automation\WinCC. Skip the project backup kept in §3.
3. Delete the keys HKLM\SOFTWARE\Siemens\WinCC and HKCU\SOFTWARE\Siemens\WinCC only after exporting a backup.
4. Reinstall WinCC v7.5 from the original media, then apply the latest Service Pack and Update in the same boot cycle.
5. Restore the project backup to WinCCProjects\<ProjectName>. Re-bind the runtime database path under Computer → Properties → Graphics Runtime.
6. Re-authorize the runtime with the original license key via Automation License Manager.

8. Verification and Functional Tests

After each remediation step, run the following acceptance suite:

Examine the diagnostic log <Project>\Diagnostics\WinCC_Sys_<log>.log for the entries GDStart, RTStart, and LicenseValid. Absence of any of these lines after the update indicates a residual problem.

9. Related Runtime Issues and Edge Cases

9.1 Endless "RT loading" after opening an existing PDL

Graphics Designer attempts to read picture-level metadata stored in <PDL>.pdl_cache. When the cache was created by an older SP level, the binary header is incompatible and the designer enters a wait state. Delete the cache directory and let the designer rebuild it.

9.2 WinCC Runtime starts but remains blank

Blank canvas is most often a graphics-driver issue on the operator station rather than a WinCC defect. Update the GPU driver, force Compatibility Mode in the shortcut, and disable Windows display scaling above 100 % for the WinCC Explorer process via Properties → Compatibility → Change high DPI settings.

9.3 Save dialog returns "File not found" but file is visible in Explorer

This is the v7.5 RTM defect referenced in the support entry above. The GDWEdit.exe binary uses an outdated SHCreateAssociationRegistration call. The update package re-links the binary against the corrected shell library.

9.4 Locked PDL files after Save As

If the file lock persists, terminate the PDLRT.exe process tree (parent HMIRuntime.exe) using taskkill /IM PDLRT.exe /T /F. Wait five seconds and clear any remaining handles with Process Explorer → Find Handle.

9.5 Migration from WinCC v7.4 / v7.3 projects

When opening a v7.4 project, WinCC v7.5 prompts to migrate. Always back up the original *.mcp and the entire project tree before accepting the migration; the migration wizard modifies *.pdl schemas in-place.

10. Preventive Maintenance Checklist

• Subscribe to Siemens Product Notification for SIMATIC WinCC V7.5. Hotfixes are released on an irregular cadence and not always announced through the standard channel.
• Schedule a quarterly task to run SIMATIC WinCC → Maintenance → Reorganize. This rebuilds the picture database and tag archive without a full restart.
• Run Windows disk cleanup on the partition hosting WinCCProjects; orphan *.bak and *.tmp files can exceed 10 GB after a few years.
• Mirror the project folder to a backup target with VSS-aware copy (e.g., wbadmin). Plain robocopy snapshots while the runtime is active produce corrupted *.pdl copies.
• Maintain a documented baseline image of the operator station, including the exact SP and Update level. This image becomes the recovery target within minutes of a service interruption.

11. Service Pack Reference Table

Always verify the latest update revision against the Siemens Industry Online Support portal before planning maintenance windows.