Postgres只是随机停止工作(Rails, PGSQL.5432)

I've been using the same Postgres database in this same app for a month with no problems, and I didn't change anything in the database before this error randomly came up today. However, today Postgres randomly started throwing this error when I try to "rails s" (I get the same type of error when running createdb or createuser):I've been using the same Postgres database in t