Postgresql: error "must be owner of relation" when changing a owner object

Thanks to Mike's comment, I've re-read the doc and I've realised that my current user (i.e. userA that already has the create privilege) wasn't a direct/indirect member of the new owning role...

So the solution was quite simple - I've just done this grant:

grant userB to userA;

That's all folks ;-)

Another requirement is that the object has to be owned by user userA before altering it...

From the fine manual.

You must own the table to use ALTER TABLE.

Or be a database superuser.

ERROR: must be owner of relation contact

PostgreSQL error messages are usually spot on. This one is spot on.

This solved my problem : Sample alter table statement to change the ownership.

ALTER TABLE databasechangelog OWNER TO arwin_ash;
ALTER TABLE databasechangeloglock OWNER TO arwin_ash;