Tablespace symlink error after changing data_directory location in PSQL 9.4
Postgres tablespaces are a symbolic link in the pg_tblspc directory. That link must appoint to a valid place for the tablespace files.

Please, make a link again, pointing to the write place.

You can see the tablespaces locations on psql client with the \db command or running the query bellow:

SELECT 
  spcname AS "Name",
  pg_catalog.pg_get_userbyid(spcowner) AS "Owner",
  pg_catalog.pg_tablespace_location(oid) AS "Location"
FROM pg_catalog.pg_tablespace
ORDER BY 1;


See the documentation for more details:

https://www.postgresql.org/docs/current/static/manage-ag-tablespaces.html