Knowledge BaseTroubleshootingTroubleshoot ZStack Cloud VM instance startup and operating system failures

Troubleshoot ZStack Cloud VM instance startup and operating system failures

TroubleshootingZCF · CloudVersions4.x-4.8.38Article IDKB-100149Updated2026-08-19

Issue/Introduction

This article applies when a VM instance fails to start or enter the operating system, the console displays a black or blue screen, the VM instance pauses abnormally or crashes, data is abnormal after a restart, or internal monitoring has no data. The issue might originate from virtual hardware configuration, system boot, file system corruption, virtio or GuestTools, QEMU logs, storage failures, a platform type mismatch after migration, or behavior inside the guest operating system.

Symptoms

  • A VM instance fails to start, displays no booting device found on the console, enters the UEFI shell, or restarts repeatedly.
  • A Windows VM instance displays a blue or black screen, starts slowly, or cannot recognize a NIC or volume after migration.
  • A VM instance pauses abnormally, times out during recovery, or crashes, and the QEMU logs contain an error such as Resource temporarily unavailable.

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Troubleshoot ZStack Cloud VM instance startup and operating system failures | KB-100149 | ZStack Resource Center