the database system is starting up

SQLSTATE 57P03 condition cannot_connect_now class 57 — Operator Intervention severity FATAL

Reproduced & verified on PostgreSQL 14.23, 15.18, 16.14, 17.10 and 18.4 — identical message on every version.

Last reviewed 30 May 2025 · Reproduced live with the SQL on this page.

Symptoms

A connection attempt arrived while the server was still starting (performing crash/archive recovery before accepting normal connections). PostgreSQL refuses with SQLSTATE 57P03 (cannot_connect_now).

Transient — connections succeed once startup/recovery finishes.
Common right after a restart or crash recovery.
Hot standby may accept read-only connections earlier.

What the server log shows

FATAL:  the database system is starting up

Why PostgreSQL raises this — what the manual says

As Section 18.5 Shutting Down the Server explains:

A connection arrived while the postmaster was still performing startup/recovery, so it cannot yet accept queries; the server replays WAL to reach a consistent state before it begins accepting normal connections.

On startup the postmaster runs recovery to bring the cluster to a consistent state before opening for connections. Until that completes, new connections are rejected with 57P03.

Common causes

Connecting during normal startup right after a restart.
A long crash-recovery replaying lots of WAL.
Slow archive recovery during restore.

How to fix it

Wait and retry with backoff until the server finishes recovery.
Make clients/pools tolerant of 57P03 during startup windows.
If recovery is slow, investigate WAL volume and I/O throughput.

Related & next steps

Reference: PostgreSQL 18 Section 19.3 “Server Start/Shutdown”.