"remaining connection slots are reserved": the 7 superuser slots

"remaining connection slots are reserved": diagnose and fix

Symptom

FATAL: remaining connection slots are reserved for roles with the SUPERUSER attribute (sometimes for non-replication superuser connections).

Cause

Neon reserves 7 connections for its superuser account. When every other slot is taken, regular roles get this instead of "too many clients already". It is the same exhaustion, one step later.

Confirm

Same as too-many-clients: SHOW max_connections, count pg_stat_activity, check the Console Monitoring graph. On a 0.25 CU compute the app budget is 104 - 7 = 97 connections.

Fix

• Move app traffic to the pooled string; this is almost always a direct-connection workload that should not be direct.
• Audit for leaked or long-held direct connections (migrations left open, scripts, BI tools on direct).
• Raise compute size if the direct workload is legitimate.

Verify

Direct connection count well under max_connections minus 7 at peak.

Neon's pooling docs (verified live 2026-09-26): 7 connections reserved for the Neon superuser; 0.25 CU example gives 97 available of 104 total; the connection error docs list this error among resolved connection errors.