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Supabase Max Client Connections Reached

Workaround available Web, server (all SDKs) Updated October 21, 2026

Quick answer

The app opened more connections than your compute size or pooler allows. Switch to the transaction pooler (port 6543), lower the client connection limit, or upgrade compute.

Most likely fix: Use the transaction pooler on port 6543.

Symptoms

Errors like 'Max client connections reached', 'too many connections for role', 'remaining connection slots are reserved' or EMAXCONNSESSION, often under load or from serverless functions.

Why it happens

  • Serverless functions (Vercel, Lambda, Edge) each open new connections
  • Session mode pooler (port 5432) capped by Pool Size, e.g. 15
  • Compute limit reached (Micro: 60 direct / 200 pooler)
  • Connections not closed by ORM or app

How to fix it

Try these in order — the most common fix is first.

  1. 1. Use the transaction pooler on port 6543

    1. Dashboard > Connect > choose Transaction pooler
    2. Replace your DATABASE_URL with that string
    3. Disable prepared statements in your client (transaction mode doesn't support them)

  2. 2. Limit connections per client

    1. For Prisma add connection_limit=1 to the URL for serverless
    2. Set a small pool size in node-postgres/Drizzle
    3. Close connections when done

  3. 3. Raise Pool Size for session mode

    1. Database Settings > Connection pooling
    2. Increase Pool Size within your compute limit

  4. 4. Check pooler logs

    1. Dashboard > Logs > Pooler
    2. Look for the client or role creating too many connections

  5. 5. Upgrade compute

    1. Project Settings > Compute and Disk
    2. Small allows 90/400 connections, Medium 120/600, Large 160/800

This guide also covers

  • supabase max client connections reached
  • supabase too many connections
  • supabase connection pool
  • supavisor connection limit

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