While playing with VMware vCenter Server Appliance in my home lab, I have been surprised with the following error:

Error: VPXD must be stopped to perform this operation.

This error has came up while trying to change authentication to active directory authentication and kinda seen the same error when trying to change the database to an external database. For some reason the Server service stop button is shadowed as well which mean I could not stop it by the GUI interface. Although my lab setup is not ideal and it might just due to the way I set it up, though I will still document how I resolved this where the same mechanism can be used to stop and restart any other service used by the vCenter Server Appliance. Below are the steps I have followed:

1- SSH to your VMware vCenter Server Appliance using the root account.

2- Execute the following command to see the status of all the service running in the vCenter Appliance:   chkconfig

The output of all services will look something like below:

localhost:~ # chkconfig
after.local               off
apache2                  off
arpd                         off
atftpd                       off
auditd                       on
autoyast                    off
chargen                      off
chargen-udp              off
cron                       on
daytime                    off
daytime-udp              off
dbus                     on
dcerpcd                  on
dhcp6r                   off
dhcp6s                   off
dhcpd                    off
discard                  off
discard-udp              off
earlysyslog              on
echo                     off
echo-udp                 off
eventlogd                on
fbset                     on
gpm                      off
haldaemon                on
haveged                  on
irq_balancer             on
kbd                      on
ldap                     on
lsassd                   off
lwiod                    on
mdadmd                   off
multipathd               off
netlogond                on
netstat                  off
network                  on
network-remotefs         on
nfs                      on
ntp                      off
pcscd                  off
powerd               off
random               on
raw                      off
rpasswdd            off
rpcbind                on
rpmconfigcheck           off
sendmail                       on
servers                           off
services                         off
setserial                        off
skeleton.compat          off
splash                            on
splash_early                on
sshd                               235
stunnel                         off
syslog                           on
syslog-collector         off
systat                          off
time                            off
time-udp                   off
uuidd                         off
vami-lighttp             235
vami-sfcb                 235
vaos                          235
vmware-inventoryservice  on
vmware-logbrowser        off
vmware-netdumper         off
vmware-rbd-watchdog      off
vmware-tools             on
vmware-vpostgres         on
vmware-vpxd              on
vsphere-client           on
xinetd                   off
ypbind                   off

3- Stop the required service in my case was vmware-vpxd using the following command: chkconfig service-name off (ex: chkconfig vmware-vpxd off)

4- carry out your changes

5- Start the service again using the following command: chkconfig service-name on (ex: chkconfig vmware-vpxd on)

I hope this help someone out there from being stuck with such issue