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Windows Agent | Installation Fails Due to Service or Event Log Registration Errors

Updated over 3 weeks ago

Overview 💥

During installation of the Liongard Windows Agent, the installer may fail when attempting to start the agent service. This issue typically presents as a service startup failure related to permissions or Windows Event Log registration conflicts.

This article explains:

  • Why the error occurs

  • How to safely remediate it

  • When to use the Liongard install script

  • When to escalate to Support

Common Error Messages 🧐

You may see one or more of the following errors during installation:

Service Liongard Agent (liongardagent.exe) failed to start. Verify you have sufficient privileges to start system services.

Or in Windows Event Viewer:

Service cannot be started. System.ArgumentException:The source LiongardAgentSVC is not registered in log LiongardAgentLog. (It is registered in log Application.) The Source and Log properties must be matched…

Why Does This Happen? 🤔

This issue is most commonly caused by:

  • ❌ Stale or incorrect Windows Event Log registry entries

  • 🔁 Previous failed installs or partial uninstalls

  • 🔐 Insufficient permissions during installation

  • 🛡️ Interference from endpoint security software (AV / EDR)

The Liongard Agent service on Windows is now named:

Component

Correct Name

Agent Service

LiongardAgent

Event Log Source

LiongardAgentSVC

If Windows has an incorrect or conflicting Event Log registration, the service cannot start—even if the binaries install successfully.

Steps to Resolve 🧑‍🏫

⚠️ Important: The steps below require local administrator privileges.

1️⃣ Open the Windows Registry Editor

  • Press Win + R

  • Type regedit

  • Press Enter

2️⃣ Navigate to the Event Log Registry Path

HKLM\SYSTEM\CurrentControlSet\Services\EventLog\Application

3️⃣ Locate the LiongardAgentSVC Key

  • Look for a registry entry named LiongardAgentSVC

4️⃣ Export the Registry Key (Strongly Recommended)

📦 This is a precautionary backup.

  • Right-click LiongardAgentSVC

  • Select Export

  • Save the file to a known location

💡 If any unexpected behavior occurs later, this key can be restored.

5️⃣ Delete the LiongardAgentSVC Registry Entry

  • Right-click LiongardAgentSVC

  • Select Delete

  • Confirm the deletion

6️⃣ Reattempt the Installation

👉 Liongard Agent Install Script

The script ensures:

  • Proper permissions

  • Clean service registration

  • Correct SYSTEM-level execution

Validation After Installation 👨‍🔧

After reinstalling, confirm:

  • ✅ Service exists: services.msc → LiongardAgent

  • ✅ Service status: Running

  • ✅ Event logs: Event Viewer → Application → No new LiongardAgentSVC errors

Security & Best Practice Notes 🗒️

🔐 Registry changes should be minimal and intentional

  • Only delete the specific LiongardAgentSVC key

  • Do not modify other Event Log entries

  • Ensure endpoint security tools are not blocking service creation

When to Contact Support 🦁

Contact Liongard Support if:

  • The service still fails to start after reinstall

  • The registry key recreates incorrectly

  • Event Viewer shows repeated startup exceptions

  • EDR/AV logs indicate blocked service activity

📎 When opening a ticket, include:

  • Agent version

  • Windows OS version

  • Installer logs (if available)

  • Relevant Event Viewer entries

Summary 🤩

  • Liongard Windows Agent service is now LiongardAgent

  • Event log source LiongardAgentSVC must be registered correctly

  • Stale registry entries can block service startup

  • Safely removing the conflicting key resolves the issue

  • Always reinstall using the official install script

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