How to upgrade ESXi 5.5 to 6.5.0 using Update Manager

The following upgrade process will explain you the step by step procedure to upgrade ESXi hosts from 5.5 to 6.5 using update manager:

Pre-upgrade check:

  • Download the ESXi 6.5 ISO image from
  • Before upgrading ESXi hosts, complete the vCenter upgrade and check the compatibility of the hardware from “VMware Compatibility Guide
  • Based on the compatibility matrix, consider to upgrade hardware BIOS firmware, drivers, HBA, NICs and partner vendor’s software vibs or include them in the baseline from update manager.
  • Check whether enough resources are available in the ESXi hosts part of the cluster to migrate virtual machines.

This upgrade process has two stages with multiple steps in each stage:

  1. Creating New Base line for “Host Upgrade”
  2. Attach baseline to host, Scan for Upgrades for compliance, Remediate to upgrade ESXi to 6.5

Stage 1: Create baseline from Update Manager.

Login to your new vCenter 6.5 web-client and select Update Manager. Go to Admin view,

Under Manage Tab, go to ESXi Images, Select Import ESXi Images option as shown below

To upload the 6.5 ESXi ISO, Browse to the ISO file path and wait to complete Upload.

Review the Imported ESXi Image and close the window and find the ISO in imported Images


Under Manage tab in update manager, go to Hosts Baselines and select +New Baseline to create baseline for ESXi 6.5 Upgrade:

New Baseline creation wizard opens, Name the baseline type and select Host Upgrade, Click next

Select the ESXi ISO image we have just uploaded and click next

Review the baseline details and click finish

You can find the New Baseline “ESXi 6.5 Upgrade” in the Hosts baselines

Stage 2: Upgrade the ESXi Host to version 6.5 using from Update Manager with the new baseline:

Migrate the virtual machines from the ESXi 5.5 to the different host in the cluster and set the host to maintenance mode.

Navigate to Update Manager tab of the ESXi host ready to upgrade and click on “Attach Baseline” to select the new Baseline created:

Select the baseline “ESXi 6.5 Upgrade” from the Upgrade Baselines to attach to the 5.5 ESXi host ready to upgrade and click ok,

Detach the unwanted baselines except this new upgrade baseline from the upgrade manager host. Select the Baseline and click Scan updates and check the host compliance status “Non-Complaint” means that host can be upgraded or needed patches. If it is “Complaint” – host is running with latest version and patches then the baseline.

Click on Remediate and follow the below Remediate options to upgrade the ESXi host with the baseline created before (means our Upgrade Baseline – ESXi 6.5 Upgrade):


Check for the Remediate status in Task bar and after completion Host will be have Compliance Status as “Complaint”.

Hope this post is helpful. Please let me know your feedback below in the comments section and reach me if you have faced any challenges during the Installation/Upgrade Process. Wish you Good Luck, stay connected for more posts…….


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