operator does not exist: timestamp with time zone + integer in PostgreSql

I came across with a strange issue in postgres. I have two databases create in two different periods.
Both are running in the same PostrgreSql 9.6 version in the same machine. When I run the query SELECT now() + 30 in database 1 -> Its working properly.
The same query I am copy paste in the second database, its giving error: operator does not exist: timestamp with time zone + integer in PostgreSql

Can some one guide me on this.

Maybe someone created the operator with those types in one database, but not in the other one.

create function addit(timestamptz,int) returns timestamptz immutable language sql as $$ 
    select $1+ interval '1 day'*$2 
$$;
create operator + (leftarg =timestamptz, rightarg =int, procedure=addit);

I have added the below query to solve the issue.

CREATE OPERATOR + ( PROCEDURE = adddays,LEFTARG = TIMESTAMPTZ, RIGHTARG = NUMERIC,COMMUTATOR = +); CREATE OPERATOR – ( PROCEDURE = adddays,LEFTARG = TIMESTAMPTZ, RIGHTARG = NUMERIC,COMMUTATOR = -);

Note: When ever I had restored the database, I used to get this issue.