Upgrade failing: pgpsql , create or replace count_estimate_smart2

Nov 28 07:49:52 vagrant okapi.sh[1933]: SLF4J: See http://www.slf4j.org/codes.html#no_static_mdc_binder for further details.
Nov 28 07:49:52 vagrant okapi.sh[1933]: 28 Nov 2019 07:49:52:859 INFO  PostgresClient [46793eqId] Executing multiple statements with id 1769295429
Nov 28 07:49:52 vagrant okapi.sh[1933]: 28 Nov 2019 07:49:52:907 INFO  PostgresClient [46841eqId] trying to execute:  SET search_path TO diku_mod_inventory_storage,  public
Nov 28 07:49:52 vagrant okapi.sh[1933]: 28 Nov 2019 07:49:52:909 INFO  PostgresClient [46843eqId] Successfully executed:  SET search_path TO diku_mod_inventory_storage,  public
Nov 28 07:49:52 vagrant okapi.sh[1933]: 28 Nov 2019 07:49:52:909 INFO  PostgresClient [46843eqId] trying to execute:  SET search_path TO public, diku_mod_inventory_storage
Nov 28 07:49:52 vagrant okapi.sh[1933]: 28 Nov 2019 07:49:52:909 INFO  PostgresClient [46843eqId] Successfully executed:  SET search_path TO public, diku_mod_inventory_storage
Nov 28 07:49:52 vagrant okapi.sh[1933]: 28 Nov 2019 07:49:52:910 INFO  PostgresClient [46844eqId] trying to execute: CREATE OR REPLACE FUNCTION diku_mod_inventory_storage.count_estimate_smart2(rows bigint, lim bigint, query text) RETURNS bigint AS $$
Nov 28 07:49:52 vagrant okapi.sh[1933]:  DECLARE   rec   record;   cnt bigint; BEGIN   IF rows = lim THEN       FOR rec IN EXECUTE 'EXPLAIN ' || query LOOP         cnt := substring(rec."QUERY PLAN" FROM ' rows=([[:digit:]]+)');         EXIT WHEN cnt IS NOT NULL;       END LOOP;       RETURN cnt;   END IF;   RETURN rows; END; $$ LANGUAGE plpgsql VOLATILE STRICT
Nov 28 07:49:52 vagrant okapi.sh[1933]: 28 Nov 2019 07:49:52:916 ERROR PostgresClient [46850eqId] ERROR: cannot change return type of existing function
Nov 28 07:49:52 vagrant okapi.sh[1933]:   Hint: Use DROP FUNCTION count_estimate_smart2(bigint,bigint,text) first.
Nov 28 07:49:52 vagrant okapi.sh[1933]: org.postgresql.util.PSQLException: ERROR: cannot change return type of existing function
Nov 28 07:49:52 vagrant okapi.sh[1933]:   Hint: Use DROP FUNCTION count_estimate_smart2(bigint,bigint,text) first.