Performing a Trellix ePolicy Orchestrator upgrade enhances system security, and improves functionality. In this article, we will discuss how to upgrade Trellix ePolicy Orchestrator (on-premise server). Please see how to Fixes to Trellix ePolicy Orchestrator Installation Errors, how to forcefully remove Language Pack on Windows 10 and 11, and How to deploy MBAM Client as part of a Windows Deployment
Upgrading your existing Trellix ePO involves careful planning and preparation for a smooth and successful process.
Here is a guide on Trellix ePolicy Orchestrator Installation on Windows Server, Windows Defender detects Endpoint Security HipHandlers.dll, and “Fixes for Trellix ePolicy Orchestrator Installation Errors“.
Prerequisites before upgrading
Before upgrading Trelix to with the latest update as shown in the table below. Check that your Trellix ePO server meets all requirements.
If yes, download the Trellix ePO software and back up your databases and directories. I would recommend having a test ePO system in place where you can perform all these tests prior to upgrading the production environment.
Make sure to review the supported upgrade paths. Use the table to decide your upgrade part or review the Supported Upgrade Paths for on-Premises ePO 5.10 Service Pack 1
Note: This package “ePO 5.10 Service Pack 1 (ePO 5.10 SP1)” can be used to install ePO for the first time and includes the updates in CU 1–15. It’s also used to upgrade some versions of ePO 5.9.1 and earlier to ePO 5.10 SP1 as well.
Also, ePO 5.10 Service Pack 1 Update (ePO 5.10 SP1 CU) can be used to upgrade an existing ePO 5.10 server to Service Pack 1. You don’t need to install this if you’ve already installed ePO 5.10 Service Pack 1.
Stop Agent Handler and Trellix ePO Services
Stop the services of the Trellix ePolicy Orchestrator (ePO) services a shown below.
Download the refreshed release of ePO 5.10 SP1 Update package. The filename name is ePO_5.10.0_1359_ServicePack1Update.zip. See KB56057 – How to download product updates and documentation for download instructions
Unzip and launch the ePOUpdate InstallShield Wizard to upgrade the ePO (on-remise server).
In the ePO Updater tool. Some of these information will be pre-populated.
Enter your password and accept the license agreement. Click continue to progress.
View the update information and improvements.
Note the following services that will be restarted. Click continue to proceed.
Hit the OK button to apply the changes
The ePO updater is applying the update.
As you can see, our update is complete. Hit the Finish button to complete the Trellix update process.
Access the ePO URL
Upon accessing the ePO URL and you are prompted with this error after the upgrade. Please clear your browser cache to proceed.
From the dashboard, click on the menu button.
You should be able to see that indeed the update was applied correctly.
Note: if you have agent handlers, you will need to repeat these instructions on all remote agent handlers
Bonus Points – Resolve Trellix Upgrade Errors
When you are prompted to remove Trellix extension before you can update the ePO.
Log into Trellix, and select extension. Click remove extension as shown below.
The problematic extension will be displayed on the screen. 
Select the button to forcefully remove the extension and click OK.
I hope you found this article on How to upgrade Trellix ePolicy Orchestrator very useful. Please feel free to leave a comment below.