PostgreSQL Relation does not exist

The cause of error: There is no table created with the specified name.
Check the table name or use IF EXISTS.

Wrong alter

ALTER TABLE 
test.clients RENAME TO customers;

Messages

ERROR: relation “test.clients” does not exist

Correct alter

ALTER TABLE IF EXISTS 
test.clients RENAME TO customers;

Messages

NOTICE: relation “clients” does not exist, skipping
ALTER TABLE