PostgreSQL 9.5.4 on x86_64-pc-linux-gnu, compiled by gcc (Debian 4.9.2-10) 4.9.2, 64-bit
(postgrespro)

select pathman.create_range_partitions('main.participant', 'pdate', '2016-01-01'::date, '1 year'::interval);
->
NOTICE: sequence "participant_seq" does not exist, skipping
WARNING: Range constraint for relation 41726 MUST have exact format: VARIABLE >= CONST AND VARIABLE < CONST. Skipping...
WARNING: Partitions 41692 and 41726 overlap. Disabling pathman for relation 29053...
NOTICE: Copying data to partitions...
ERROR: ERROR: Cannot find partition P0001

select * from main.participant
->
ERROR: could not open relation with OID 2147483649

• several rows in
  create table main.participant
  (
  tid bigint not null,
  cid integer not null,
  pdate date not null,
  ...
  primary key (tid, cid)
  )