VMware Horizon Agent “Protocol Error” — Fixed by Windows Firewall Configuration
🖥️ VMware Horizon Agent “Protocol Error” — Fixed by Windows Firewall Configuration Overview Recently, I encountered an issue where several Horizon Agent–based virtual desktops in our environment showed the status “Starting other services” or “Protocol Error” in the Horizon Administrator console. Even after reinstalling the Agent (version 2206 ), the problem persisted. Symptoms Horizon Agent status: “Starting other services” → “Protocol error” Horizon main services appeared to be running normally Event Viewer showed Event ID 7000 for services such as: PASVC – failed to start LUFAV – not installed Reinstalling the Agent (even using Repair mode ) did not solve the issue Root Cause After deeper inspection, we discovered that on the affected VMs: Windows Defender Firewall (Domain Profile) → “Block all incoming connections, including those in the list of allowed apps” was checked (enabled). This setting silently blocks all inbound traffic , ev...