PostgreSQL error 08006 connection_failure signals that the client could not establish or maintain a connection to the server.
PostgreSQL connection_failure (08006) occurs when the client cannot open or keep a network session with the database. Check server status, network rules, and authentication files first – restarting the server or fixing pg_hba.conf usually clears the error.
PostgreSQL connection_failure (08006)
PostgreSQL raises SQLSTATE 08006 when a client fails to create or retain a TCP session with the server process. The message appears during startup or mid-query and forces the session to close.
The error belongs to class 08 Connection Exception, meaning root causes lie outside SQL syntax and inside transport, authentication, or server availability layers.
Client libraries emit 08006 during initial handshake, after SSL negotiation, or while reading results if the socket breaks.
It is common when servers crash, firewalls drop idle connections, or max_connections is exhausted.
Interactive tools like psql, application pools, or IDEs such as Galaxy will surface the same failure code whenever the backend disappears unexpectedly.
Unresolved connection failures stall applications, cause transaction rollbacks, and may hide deeper infrastructure issues.
Persistent 08006 events can exhaust retries and cascade into user-visible downtime.
Prompt diagnosis avoids wasted compute cycles, protects data consistency, and restores service quickly.
Network filters, incorrect hostnames, and wrong ports stop the TCP handshake. PostgreSQL instantly throws 08006.
Server‐side limits such as max_connections or crashed postmaster terminate incoming sessions, yielding the same code.
Verify the server process with systemctl or pg_ctl. If down, restart it.
Confirm the host, port, and SSL mode in the connection string.
Adjust and retry.
Inspect pg_hba.conf and reload the config so that the client’s IP and auth method match.
Increase max_connections or tune connection pooling if the log shows “sorry, too many clients”.
Firewall drops idle sockets – raise tcp_keepalives_idle and server parameters.
SSL certificate mismatch – update client root CA or regenerate server certs.
Employ a connection pooler (PgBouncer) to cap open sessions and provide fast failover.
Monitor pg_stat_activity and system logs for early signs of connection churn.
08003 connection_does_not_exist – occurs after connection_failure if the app retries on a dead socket.
Fix networking first.
57P01 admin_shutdown – indicates the server closed connections due to shutdown. Investigate maintenance scripts.
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Typoed DNS names, wrong port numbers, or closed interfaces deny the TCP handshake and trigger 08006 instantly.
If postmaster is stopped or crashes, new clients receive connection_failure until the service restarts.
Network devices that block or time out idle sessions break the socket mid-query, surfacing the error.
When active sessions meet the server limit, new attempts fail with 08006 until a slot frees up.
Expired certificates or mismatched SSL modes cause the server to abort the negotiation, returning connection_failure.
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No. Transactions not yet committed are rolled back, but committed data stays intact. Resolve connectivity and rerun the statement.
No. Any layer between client and server can cause it: VPNs, proxies, TLS, or misconfigured clients.
Galaxy’s built-in connection tester validates host, port, and SSL before executing queries, catching most mistakes early.
Short automatic retries are acceptable, but log incidents and investigate persistent failures to avoid endless loops.
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