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Database & ORM · Developer Error Resolution Lab

Fix PostgreSQL 'FATAL: remaining connection slots are reserved for non-replication superuser connections'

Resolve PostgreSQL connection exhaustion caused by connection leaks or missing pooling with PgBouncer / Prisma Accelerate.

Triggered Error Message:

FATAL: remaining connection slots are reserved for non-replication superuser connections

Customize Solution for Your Environment
# PostgreSQL Configuration Fix (postgresql.conf)
max_connections = 200
shared_buffers = 512MB

# Terminal Emergency Unlock (Kill idle connections):
psql -U postgres -c "SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE pid <> pg_backend_pid() AND state = 'idle';"

# Recommended: Enable connection pooling in database URL:
# DATABASE_URL="postgresql://user:pass@host:5432/db?connection_limit=10&pool_timeout=20"

Root Cause & Mechanism Analysis

Why does this error occur?

Active database connections reached `max_connections` (default 100). Serverless functions or application instances without connection pooling leak idle connections until exhaustion.

Frequently Asked Questions

Why is raising max_connections alone not recommended?
Each PostgreSQL connection consumes ~10MB RAM. Excessive connections cause RAM thrashing. A connection pooler like PgBouncer is required for high concurrency.

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