Error 57P03 (cannot_connect_now) occurs when a client tries to connect while the PostgreSQL server is starting, shutting down, or in recovery.
PostgreSQL Error 57P03 (cannot_connect_now) signals that the server is not ready to accept connections because it is starting up, shutting down, or recovering. Wait for the server to reach a steady state or cancel the disruptive operation, then reconnect.
PostgreSQL Error 57P03
Error 57P03 tells the client that the server cannot accept connections right now. PostgreSQL raises it when the instance is starting, shutting down, in crash recovery, or in hot-standby promotion. Until the server reaches normal mode, connection attempts are refused.
The error appears immediately after the TCP handshake, so applications see it as a PostgreSQL error, not a network failure.
Monitoring tools also log it, making it easy to detect startup or shutdown windows.
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Typical triggers include service restarts, automated failovers, pg_ctl stop commands, and cloud-provider maintenance. Connection pools open sockets too early and receive the 57P03 code until the postmaster finishes recovery.
Long-running recovery on large WAL archives can expose the error for several minutes. Users must design retry logic or pause traffic during these windows to avoid application outages.
Unhandled 57P03 errors cause application downtime, failed health checks, and broken CI pipelines. Proper handling guarantees graceful startup, smoother rolling deploys, and predictable failover behavior.
Addressing the root cause also prevents misleading alerts: distinguishing genuine outages from controlled restarts keeps on-call noise low.
The server is in startup mode and has not finished reading the control file or WAL.
The server is in shutdown mode after receiving pg_ctl stop, systemctl stop, or a SIGTERM.
The server is in recovery after crash or replica promotion and has not reached consistent state.
Configuration hot_standby = off on a replica blocks reads until recovery ends, triggering the error for read-only users.
High availability tools (Patroni, repmgr) briefly reject connections while rewinding or promoting nodes.
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First confirm the server state with pg_isready or systemctl status. If the server is still starting, wait until pg_isready returns "accepting connections." If shutting down, cancel the stop action or start the service again.
Ensure connection pools implement exponential backoff retries. For psql scripts, add the --wait flag or wrap with a loop that sleeps and retries.
Check recovery.conf or postgresql.auto.conf on replicas.
Enable hot_standby = on so read-only clients can connect during recovery.
Investigate long recovery times by tuning checkpoint_completion_target and increasing max_wal_size to reduce crash recovery duration.
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Rolling restarts - Orchestrate in-service health checks that wait for pg_isready before routing traffic.
Cloud maintenance - Use multi-AZ or read replica failover so clients can reconnect elsewhere.
CI/CD tests - Add retry logic with psql --set ON_ERROR_STOP=1 and loop until pg_isready returns 0.
Hot-standby promotion - Promote with pg_ctl promote then poll pg_is_in_recovery() = false before re-enabling writes.
Automate health probes with pg_isready and only mark pods ready when status is "accepting connections."
Configure application connection pools (e.g., pgbouncer, HikariCP) to retry on SQLSTATE 57P03 with increasing delays.
Run checkpoint; before planned restarts to minimize recovery time.
Maintain smaller WAL segments or faster storage to speed crash recovery, reducing the window where 57P03 appears.
Galaxy users can embed pg_isready checks in run workflows and share trusted restart scripts, ensuring teammates follow the same safe procedure.
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SQLSTATE 53300 (too_many_connections) - Server is up but connection limit reached. Increase max_connections or use pooling.
SQLSTATE 08001 (sqlclient_unable_to_establish_sqlconnection) - Generic network failure, often firewall or wrong host.
SQLSTATE 57P02 (crash_shutdown) - Server is shutting down after a crash; investigate logs.
Solutions differ: 57P03 needs waiting, 53300 needs tuning, 08001 needs networking fixes, 57P02 needs crash analysis.
The postmaster is still reading WAL and has not reached consistent state, so it rejects all clients.
An administrator issued pg_ctl stop or systemctl stop, moving the server into shutdown mode.
PostgreSQL replays WAL to reach a consistent point, blocking connections until complete.
Read-only connections are blocked on replicas until recovery ends when hot_standby is disabled.
Tools like Patroni temporarily refuse connections while rewinding or promoting nodes.
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On a normal restart it lasts a few seconds. During large crash recovery it can last minutes, depending on WAL volume and I/O speed.
No. PostgreSQL intentionally blocks connections until the database is consistent. On replicas you can enable hot_standby to allow reads.
Start with 3–5 retries using exponential backoff up to 30 seconds. Most servers will be ready within that window.
Galaxy lets teams script pg_isready checks in shared notebooks, endorse safe restart procedures, and add connection-retry snippets to queries so editors do not fail during restarts.
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