error 409 when configuring a Net-Net system

When trying to change an object in the configuration, you must first 'select' it in order to modify it. Below is an example of trying to modify the system-config, without first selecting it.

 

acme(system-config)# done
error 409 saving system config
acme(system-config)# 

acme(system-config)# 
acme(system-config)# exit
Save Changes [y/n]?: y
error 409 saving system config
acme(system)# 

Here is the same process, changing the description field but first selecting it:

 

acme(system-config)# select
acme(system-config)# description test
acme(system-config)# done
system-config
hostname 
description test
location 
mib-system-contact 
mib-system-name 
mib-system-location 
snmp-enabled enabled
enable-snmp-auth-traps disabled
enable-snmp-syslog-notify disabled
enable-snmp-monitor-traps disabled
enable-env-monitor-traps disabled
snmp-syslog-his-table-length 1
snmp-syslog-level WARNING
system-log-level WARNING
process-log-level NOTICE
process-log-ip-address 0.0.0.0
process-log-port 0
collect
sample-interval 5
push-interval 15
boot-state disabled
start-time now
end-time never
red-collect-state disabled
red-max-trans 1000
red-sync-start-time 5000
red-sync-comp-time 1000
call-trace disabled
internal-trace disabled
log-filter all
default-gateway 10.0.0.0
restart enabled
exceptions 
telnet-timeout 0
console-timeout 0
remote-control enabled
cli-audit-trail enabled
link-redundancy-state disabled
source-routing disabled
last-modified-date 2008-12-03 14:44:07