idempiere: cannot add city to bpartner location

the error reads:

The city does not exist and can not created from here.

solution:

if you open up the idempiere log (/opt/idempiere/log) you can see that there's a problem with a duplicate c_location_id. it can be easily solved with an update query as shown below.

update
   ad_sequence
set
   currentnext = (
   (
select
      max(c_location_id)::int
   from
      c_location
   ) + 1)
where
   ad_sequence_id = 60;