PostgreSQL 9.6.17 COALESCE function error

I’m trying a SQL query with the function COALESCE in PostgreSQL 9.6.17, but it produces an error:

invalid syntax for type double precision: ""

Example query:

SELECT COALESCE(date_part('year', s.date_pp),'') FROM public.sendoc s. 

This query is working on PostgreSQL 9.3.17.

How to get around the error at the server DB level without changing the source code of the program?