Only Acronis Virtual Appliance x64 version can be used with ESXi 6.5. The x86 version of Virtual Appliance that comes in installer by default works only for ESXi 6.0 and older.

This document is composed by Acronis Disaster Recovery Service technical support and intended for Acronis Disaster Recovery Service customers who are using Acronis Backup Advanced 11.x transport. The document describes the update procedure for Acronis Agent for ESXi Virtual Appliances if you are using ESXi version 6.5. The Virtual Appliances update should be performed by any Acronis Disaster Recovery users who protects their Virtual Machines on the hypervisor level. To update Acronis Agent for Microsoft Hyper-V please follow the Acronis Agents Manual Update Guide.

Updating existing Virtual Appliance on your ESXi 6.5 host

1. Open each of your existing Acronis Virtual Appliance console using your vSphere client. Take a screenshot and save it somewhere to keep its parameters.

2. Open Acronis Management Console, connect to AMS, open Machines with agents -> All machines with agents, highlight the Virtual Appliance that you've taken a screenshot of in Step 1 and "Delete machine from AMS"
   

3. Click "Yes" then proceed with the "Installing new Virtual Appliance on your ESXi 6.5 host" part below. Use the previously saved settings in the Step 4 while configuring the new Virtual Appliance.
4. You can delete the older Acronis Virtual Appliance VM from your vCenter and storage.

Installing new Virtual Appliance on your ESXi 6.5 host

1. Download the Virtual Appliance .ovf template here.
2. Unpack and deploy the .ovf template onto your host on any storage as per your convenience:

You shall connect the Virtual Appliance to the network, that have unrestricred access to the ESXi 6.5 host management network.

3. Click Close

4. First of all, configure the IP address of the Virtual Appliance. Then connect it to your vCenter, set up the Name and the Timezone.