ESXi Upgrade Without vCenter Guide

This guide covers methods to upgrade ESXi hosts when vCenter is unavailable or non-functional.

đź“ť Note: For a comprehensive automated upgrade solution, see the ESXi 8.0U3 Upgrade Guide which documents our successful Intel NUC6i7KYK homelab upgrade using offline bundles and automation.

Table of Contents

Overview

Upgrading ESXi without vCenter is fully supported but requires manual intervention on each host. This is useful when:

  • vCenter is offline or has issues (like expired certificates)
  • Managing standalone ESXi hosts
  • Performing emergency upgrades
  • Testing new ESXi versions

Limitations Without vCenter

  • No vMotion available (VMs must be powered off)
  • No automated orchestration
  • No Update Manager/Lifecycle Manager
  • Each host must be upgraded individually
  • No centralized compatibility checks

Upgrade Methods

Quick Comparison

Method Downtime Required Complexity Best For
Interactive ISO Yes Easy Single hosts, major upgrades
ESXCLI Yes Medium Remote upgrades, patches
USB/SD Card Yes Easy Multiple identical hosts

Pre-Upgrade Checklist

1. Verify Hardware Compatibility 

# Check current version
vmware -vl

# Verify hardware is on HCL for target version
# https://www.vmware.com/resources/compatibility/search.php

2. Backup Critical Items

  • VM configurations (VMX files)
  • Critical VM data

  • Host configuration

    # Backup host configuration
vim-cmd hostsvc/firmware/backup_config
# Download from http://[ESXi-IP]/scratch/downloads/

3. Document Current Settings

  • Network configuration (vSwitches, port groups)
  • Storage configuration (datastores, paths)
  • Security settings (firewall rules)
  • Third-party VIBs installed

4. Prepare VMs 

# List running VMs
vim-cmd vmsvc/getallvms

# Gracefully shutdown VMs
vim-cmd vmsvc/power.shutdown [vmid]

Method 1: Interactive ISO Upgrade

Steps

  1. Download ESXi ISO
    • Get from VMware Customer Connect
    • Verify checksum
  2. Create Bootable Media
    • Burn to DVD/USB
    • Or mount via remote console (iLO/iDRAC/IPMI)

  3. Boot from ISO

    - Reboot host
- Enter BIOS/Boot Menu
- Select boot device
  4. Run Upgrade
    • Select “Upgrade ESXi, preserve VMFS datastore”
    • Select target disk (usually shows current install)
    • Confirm upgrade
  5. Complete Process
    • Remove boot media
    • Reboot
    • Verify upgrade successful

Verification 

# After reboot, verify version
vmware -vl

# Check all datastores are mounted
esxcli storage filesystem list

Method 2: Command Line Upgrade

Using Offline Bundle

  1. Enable SSH

    # From DCUI (Direct Console)
F2 → Troubleshooting Options → Enable SSH

  2. Upload Offline Bundle

    # Download offline bundle from VMware
# Upload to datastore via:
- SCP: scp VMware-ESXi-7.0U3o-*.zip root@[ESXi-IP]:/vmfs/volumes/datastore1/
- Datastore browser in host client

  3. Check Available Profiles

    esxcli software sources profile list -d /vmfs/volumes/datastore1/VMware-ESXi-7.0U3o-*.zip

  4. Perform Upgrade

    # Put host in maintenance mode
esxcli system maintenanceMode set --enable true

# Run upgrade (example for 7.0 U3o)
esxcli software profile update -p ESXi-7.0U3o-21930508-standard \
  -d /vmfs/volumes/datastore1/VMware-ESXi-7.0U3o-21930508-depot.zip

# Reboot
reboot

Using Online Depot

  1. Enable HTTP Client

    esxcli network firewall ruleset set -e true -r httpClient

  2. List Available Profiles

    esxcli software sources profile list \
  -d https://hostupdate.vmware.com/software/VUM/PRODUCTION/main/vmw-depot-index.xml \
  | grep -i ESXi-7.0

  3. Update to Specific Profile

    esxcli software profile update \
  -p ESXi-7.0U3o-21930508-standard \
  -d https://hostupdate.vmware.com/software/VUM/PRODUCTION/main/vmw-depot-index.xml

Method 3: USB/SD Card Upgrade

Creating Bootable USB

  1. Using Rufus (Windows)
    • Select ESXi ISO
    • Choose GPT partition scheme
    • Use FAT32 file system
    • Create bootable drive

  2. Using dd (Linux/Mac)

    # Find USB device
diskutil list  # macOS
lsblk          # Linux

# Write ISO (example for macOS)
sudo dd if=VMware-ESXi-7.0U3o.iso of=/dev/rdisk2 bs=1m
  3. Boot and Upgrade
    • Same process as Interactive ISO method
    • Select “Upgrade ESXi, preserve VMFS datastore”

Post-Upgrade Tasks

1. Exit Maintenance Mode 

esxcli system maintenanceMode set --enable false

2. Verify System 

# Check version
vmware -vl

# Verify storage
esxcli storage filesystem list

# Check network
esxcli network ip interface list

# Review VIBs
esxcli software vib list

3. Reinstall Third-Party VIBs 

# If needed, reinstall custom VIBs
esxcli software vib install -v /path/to/vib

4. Power On VMs 

# List VMs
vim-cmd vmsvc/getallvms

# Power on VMs
vim-cmd vmsvc/power.on [vmid]

5. Re-add to vCenter

Once vCenter is operational:

vCenter → Hosts and Clusters → Add Host

Troubleshooting

Common Issues

  1. “No Network Adapters” Error
    • Check if network drivers are included in ISO
    • May need custom ISO from vendor

  2. Datastore Not Found After Upgrade

    # Rescan storage
esxcli storage core adapter rescan --all
  3. VMs Won’t Start
    • Check VM compatibility with new version
    • Verify VM hardware version
    vim-cmd vmsvc/get.config [vmid] | grep version
  4. Purple Screen (PSOD)
    • Often hardware compatibility issue
    • Check HCL for your hardware
    • Try previous version

Rollback Procedure

If upgrade fails:

  1. Boot from previous ESXi installer
  2. Select “Install ESXi, preserve VMFS”

  3. Restore configuration backup:

    vim-cmd hostsvc/firmware/restore_config /tmp/configBundle.tgz

Best Practices

  1. Test First: Always test upgrades in non-production environment
  2. Upgrade Order: For multi-host environments without vCenter:
    • Upgrade one host completely
    • Verify functionality
    • Proceed with remaining hosts
  3. Timing: Schedule during maintenance windows
  4. Documentation: Keep detailed notes of any issues or changes

This project is for educational and home lab purposes.