Resolving LOGO! Soft Comfort V8.4 Java Virtual Machine Launch

Resolving LOGO! Soft Comfort V8.4 Java Virtual Machine Launch Error

Siemens LOGO! Soft Comfort V8.4 is the official engineering tool for the LOGO! 8 logic module family (6ED1052-xxx08-0BA1 base modules and BM/AM/TDE variants). The V8.4 release marked an internal infrastructure change: the bundled JRE moved from Oracle Java to the Amazon Corretto distribution. On a small but reproducible set of Windows 10 workstations, this migration surfaces a fatal launch error:

Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

This reference documents the affected build versions, the underlying root causes, the diagnostics to confirm the failure path, and the exact field-proven resolution procedure. The procedure is derived from Siemens Industry Online Support engineering notes and reproducible install traces captured on Windows 10 22H2 / Windows 11 23H2 hosts.

1. Affected Versions and Build Matrix

The JVM launch error is specific to a narrow set of builds. Use the table below to confirm you are on an affected release before applying the resolution.

Siemens no longer publishes the V8.3 or the original V8.4 full installer. The V8.4.1 update must be applied on top of a working V8.2.1 baseline. Engineers that skipped V8.2.1 and attempted a direct install of V8.4 are the most common case where the JVM launch failure becomes unrecoverable until a clean uninstall is performed.

2. Root Cause Analysis

Three independent failure paths converge on the same "Could not create the Java Virtual Machine" string. Confirm which path you are on before applying a fix.

2.1 Path A — Corretto vs. Oracle JRE Conflict

V8.4 ships with Amazon Corretto 11 as the bundled runtime. On hosts that already have Oracle JDK 24 (or any 17+ build) installed for other engineering tools, the launcher picks up the wrong JAVA_HOME from PATH precedence. Corretto 11 and Oracle 24+ cannot share a launcher classpath because the module boot layout and the InstallAnywhere LAX launcher expect specific minor versions.

2.2 Path B — Heap Size (-Xmx) Mismatch

The V8.4 launcher enforces a minimum and maximum -Xmx setting that V8.2.1 did not. Engineers that bumped the value to 6 GB (6144m) on a 4 GB-RAM workstation trigger an OOM during VM creation rather than during program execution. The error string is identical to a missing JRE.

2.3 Path C — Corrupted Upgrade State

Running the V8.4 upgrade on top of a partially failed V8.2.1 install leaves orphaned .lax, .properties, and uninstall registry entries. Once the install directory is in this state, the bundled uninstaller itself throws the JVM error and cannot be used to clean up.

3. Pre-Installation Checklist

Before modifying any file, verify the host meets the LOGO! Soft Comfort V8.4 prerequisites.

1. OS: Windows 10 (1809 or later, 64-bit) or Windows 11 (21H2 or later, 64-bit). 32-bit Windows is not supported by V8.4.
2. RAM: Minimum 4 GB, recommended 8 GB. If RAM is 4 GB, do not set -Xmx above 2048m.
3. Disk: 1.5 GB free on the system drive (C:).
4. Privileges: Local administrator account. The InstallAnywhere-based setup writes to %ProgramFiles%, %ProgramData%, and HKLM\SOFTWARE.
5. Existing Java inventory: Run where java in an elevated cmd.exe. Note the order — that order defines the launcher classpath.
6. Existing LOGO! Soft Comfort inventory: Check HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall for any prior LOGO!SoftComfort entries.
7. Network: Online update path requires HTTPS to support.industry.siemens.com and the AWS-hosted download CDN.

4. Java Runtime Configuration

The V8.4 launcher uses an InstallAnywhere LAX bootstrap file. Two parameters inside this file control the JVM.

4.1 Locate the LAX file

Default path on a 64-bit install:

C:\Program Files (x86)\Siemens\Automation\LOGO! Soft Comfort V8.4\start.lax
C:\Program Files\Siemens\Automation\LOGO! Soft Comfort V8.4\start.lax

4.2 Required parameter block

Open start.lax in a text editor running as Administrator and confirm the following keys are present and correctly set for your memory budget:

4.3 Why 6 GB (-Xmx6144m) Fails

Setting -Xmx6144m on a 4 GB workstation forces the JVM to reserve a 6 GB heap on a host that physically cannot back it. The Windows memory manager rejects the allocation request during os::create_Java_vm, and the launcher prints the generic "Could not create the Java Virtual Machine" message. Drop the value to 1024m or 2048m and re-launch.

4.4 System-Wide JAVA_HOME Strategy

If you must keep Oracle JDK 24 (or any 17+ build) for unrelated tools such as TIA Portal V18 add-ins, isolate the LOGO! launcher from the system PATH:

1. Open System Properties → Environment Variables.
2. Move Oracle paths to a per-user variable, not the system Path.
3. Keep the Corretto 11 bin path first in the system Path:

C:\Program Files\Amazon Corretto\jdk11.x.y.z_xx\bin

This guarantees the LOGO! launcher resolves java.exe to Corretto 11 first while Oracle remains available to TIA Portal through a per-user launch script.

5. Clean Uninstall Procedure (Recovery from Path C)

Use this procedure only when the bundled uninstaller also fails with the JVM error. It is the only field-proven path to recover from a corrupted V8.4 install.

1. Open Task Manager (Ctrl+Shift+Esc). End any java.exe, javaw.exe, or jdk-*.exe process belonging to LOGO! Soft Comfort.
2. Open regedit as Administrator and navigate to:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall

3. Sort by DisplayName and delete every key whose DisplayName string contains LOGO! Soft Comfort, LogosoftComfort, or LOGOComfort.
4. Delete the product keys themselves:

HKEY_LOCAL_MACHINE\SOFTWARE\Siemens\LOGOComfort
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Siemens\LOGOComfort
HKEY_CURRENT_USER\SOFTWARE\Siemens\LOGOComfort

5. Delete the install directories (default paths):

C:\Program Files\Siemens\Automation\LOGO! Soft Comfort V8.4
C:\Program Files (x86)\Siemens\Automation\LOGO! Soft Comfort V8.4
%ProgramData%\Siemens\Automation\LogosoftComfort

6. Delete the per-user project cache (only if you have already exported your LSC programs):

%AppData%\Siemens\LogosoftComfort
%LocalAppData%\Siemens\LogosoftComfort

7. Reboot. Confirm in Task Manager that no java.exe is loaded before continuing.
8. Insert the V8.2.1 media (or mount the ISO) and install. Verify it launches successfully.
9. Apply the V8.4.1 update package on top of the verified V8.2.1 baseline.

6. Step-by-Step Resolution (In-Place Repair)

Use this procedure when the V8.4 install still launches the bundled uninstaller without throwing the JVM error.

1. Close LOGO! Soft Comfort and stop the LOGOComfortServer service if it is running:

sc stop "Siemens LOGOComfortServer"
sc query "Siemens LOGOComfortServer"

2. Open Apps & Features. Locate LOGO! Soft Comfort V8.4. Click Uninstall.
3. If the uninstaller fails, jump to Section 5 (Clean Uninstall Procedure).
4. Reinstall V8.4.1 from the Siemens download portal.
5. Edit start.lax per Section 4 before the first launch.
6. Launch from a fresh cmd.exe session with the workspace explicitly set:

cd "C:\Program Files\Siemens\Automation\LOGO! Soft Comfort V8.4"
start.lax

6. Confirm the splash screen advances past the logo to the workspace selector.

7. Diagnostic Commands

Use these commands in an elevated cmd.exe to confirm the JVM state of the host before re-launching LOGO! Soft Comfort.

7.1 Java Resolution Order

where java
where javaw
where javac

The first line returned is the JRE the launcher will resolve. If it points to Oracle 24 instead of Corretto 11, see Section 4.4.

7.2 Corretto 11 Health Check

"C:\Program Files\Amazon Corretto\jdk11.x.y.z_xx\bin\java.exe" -version

Expected output:

openjdk version "11.0.xx" 2024-xx-xx LTS
OpenJDK Runtime Environment Corretto-11.0.xx.xx (build 11.0.xx+xx-LTS)
OpenJDK 64-Bit Server VM Corretto-11.0.xx.xx (build 11.0.xx+xx-LTS, mixed mode)

7.3 Heap Allocation Test

Reproduce the launcher's heap request outside LOGO! Soft Comfort to confirm the host can honor the -Xmx setting:

java -Xmx2048m -version
java -Xmx1024m -version

If the 2048m call fails on a 4 GB workstation, drop the LAX -Xmx to 1024m.

7.4 LAX File Sanity Check

Confirm the LAX file is valid UTF-8 and not truncated:

findstr /C:"lax.nl.java.option.additional" "C:\Program Files\Siemens\Automation\LOGO! Soft Comfort V8.4\start.lax"

8. Verification Procedure

Run the following checks to confirm the JVM launch error is fully cleared.

1. Cold launch test: Reboot the workstation. Launch LOGO! Soft Comfort V8.4 with no other Java tool running. Confirm the workspace loads.
2. Online update test: Open Help → Update. Confirm the updater can reach the Siemens update service.
3. Project open test: Open a known-good .lsc project from %AppData%\Siemens\LogosoftComfort. Confirm the FBD/Ladder diagram renders.
4. LOGO! 8 connection test: Connect to a LOGO! 8 base module (6ED1052-1MD08-0BA1 or similar) over Ethernet. Push and pull a configuration.
5. Long-run test: Leave the tool open for 30 minutes. Confirm no silent JVM crash dump appears in %LocalAppData%\Siemens\LogosoftComfort\hs_err.
6. Uninstall dry run: Open Apps & Features. Confirm the V8.4 entry now uninstalls cleanly without the JVM error.

9. Troubleshooting Matrix

Match the symptom to the corrective action.

10. Field-Engineered Edge Cases

10.1 Coexistence with TIA Portal V18 / V19

TIA Portal V18 and V19 ship their own OpenJDK 17 bundle. If TIA Portal is installed after LOGO! Soft Comfort V8.4, the TIA installer rewrites the system Path and the LOGO! launcher may resolve to OpenJDK 17 first. Pin the Corretto 11 path in front of the TIA path in the system Path variable.

10.2 Corporate Group Policies and AppLocker

Some enterprise group policies block unsigned Java executables from running outside %ProgramFiles%. The bundled Corretto 11 ships signed by Amazon. If AppLocker blocks java.exe, add an explicit publisher rule for Amazon Corretto in the allow list.

10.3 Virtual Machine and Hyper-V Hosts

Running LOGO! Soft Comfort inside a Hyper-V VM with dynamic memory assigned can cause the -Xmx allocation to fail intermittently as the VM balloon driver reclaims RAM. Set a fixed memory limit on the VM and reduce -Xmx to 1024m.

10.4 Anti-Virus Interference

Symantec Endpoint Protection, CrowdStrike, and Trend Micro have been observed to quarantine the bundled jdk-11.x.y.z_xx\bin\java.exe on first launch. Add an AV exception for the entire V8.4 install directory and re-launch.

10.5 Non-Default Install Path

If you installed to a path with spaces or non-ASCII characters (for example D:\Projets\A&E\_Outillage), the InstallAnywhere LAX parser can fail. Reinstall to C:\Siemens\LSC84 to confirm the path is not the trigger.

11. Preventive Configuration

After a successful install, lock in the working configuration with these two preventive steps.

1. Create a scheduled task that runs weekly and confirms the Corretto 11 path is first in Path:

echo %PATH% | findstr /B /C:"C:\Program Files\Amazon Corretto\jdk11"

2. Export the registry keys that hold the LAX overrides so they can be reapplied after a Windows feature update:

reg export "HKLM\SOFTWARE\Siemens\LOGOComfort" C:\Backup\logo_lax.reg /y

12. References and Standards

Cross-check the V8.4 toolchain against the following official Siemens documents when validating the resolution on your site.

• LOGO! 8 System Overview — product family and module catalog.
• Siemens Industry Online Support — firmware notes, KB articles, and download portal for LOGO! Soft Comfort V8.4.1.
• LOGO! 8 Base Module manual (6ED1052-xxx08-0BA1) — for the programming interface contract that LOGO! Soft Comfort implements.
• AWS Corretto 11 release notes — for runtime behavior on Windows 10 / 11.
• Oracle JDK 24 release notes — for compatibility verification when both runtimes are present on the same host.

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