Double check the version of the VirtualCenter Agent:

# rpm -qa grep vpxa

(For Example) VMware-vpxa-2.0.1-32042

To stop mgmt-vmware:

# service mgmt-vmware stop

Stopping VMware ESX Server Management services:

VMware ESX Server Host Agent Services [ OK ]

VMware ESX Server Host Agent Watchdog [ OK ]

VMware ESX Server Host Agent [ OK ]

To stop vpxa:

# /etc/init.d/vmware-vpxa stop

Stopping vmware-vpxa: [ OK ]

Uninstall vpxa:

# rpm -e VMware-vpxa-2.0.1-32042

Stopping vmware-vpxa: [ OK ]

warning: /etc/vmware/vpxa.cfg saved as /etc/vmware/vpxa.cfg.rpmsave

To make sure vpxa is no longer there:

# rpm -qa grep vpxa

# rpm -qa grep vpx

Restart up mgmt-vmware service:

# service mgmt-vmware start

Starting VMware ESX Server Management services:

VMware ESX Server Host Agent (background) [ OK ]

Availability report startup (background) [ OK ]

After reconnecting to the VI3 host from VirtualCenter, double check to make sure the version of the VirtualCenter Agent is right:

# rpm -qa grep vpxa

VMware-vpxa-2.0.1-33643

This example uses 2.0.1, but instructions are still valid for all 2.x versions of VirtualCenter and ESX 3.x