Troubleshoot a black VM instance console in ZStack Cloud

Issue/Introduction

This article provides a structured process for troubleshooting a black screen after opening a ZStack Cloud VM instance console. A black console does not necessarily mean that the VM instance failed to start. It might be caused by the console protocol, graphics type, guest operating system graphical interface, a post-migration driver, GPU passthrough, a Windows tool, or an abnormal program inside the operating system.

Symptoms

• The cloud platform console window opens, but the screen remains black or does not display a sign-in interface for a long time.
• The VM instance is accessible through SSH, Remote Desktop, or a workload port, but VNC or the console is black.
• After migration or import, a Linux or Windows VM instance starts with a black console.
• A GPU-passthrough VM instance or a VM instance on which GuestTools was installed restarts with a black screen.