赋权语句没有问题，方法也是正确的，不应该出现的错误。能发一下具体的实验案例么？我按照您说的方法试了下也没复现

postgres=# create schema test_sc AUTHORIZATION postgres ;
CREATE SCHEMA
postgres=# set search_path = test_sc ;
SET
postgres=> \du utest
           List of roles
 Role name | Attributes | Member of
-----------+------------+-----------
 utest     |            | {}

postgres=# grant usage on schema test_sc to utest;
GRANT
postgres=# grant select,insert,update,delete on all tables in schema test_sc to utest;
GRANT
postgres=# alter default privileges  in schema test_sc grant select,insert,update,delete on tables to utest;
ALTER DEFAULT PRIVILEGES
postgres=# create table test_sc(a int) ;
CREATE TABLE
postgres=# insert into test_sc values (1) ;
INSERT 0 1
postgres=# \c - utest
You are now connected to database "postgres" as user "utest".
postgres=> select * from test_sc.test_sc ;
 a
---
 1
(1 row)

postgres=> insert into test_sc.test_sc values (2) ;
INSERT 0 1
postgres=> select * from test_sc.test_sc ;
 a
---
 1
 2
(2 rows)

postgres=>