PostgreSQL - ERROR: column "date" cannot be cast to type date -

i want cast specific column in postgresql database character_varying type type date. phppgadmin gives me following error:

error: column "date" cannot cast type date

in statement: alter table "public"."tablename" alter column "date" type date

what should ? thanks

you might need convert text first:

alter table "foo" alter column "date" type date using ("date"::text::date);