Why Does the Postgres Node Fail with 'Connection Refused' Errors in n8n v1.78.1 during Looped Workflows?

Below is a list of things to check and try to resolve the issue:

1. Review Connection Settings

n8n’s Postgres credential configuration provides options like Connection Timeout and Delay Closing Idle Connection that affect how long a connection stays open when idle. Running many iterations in loops may eventually exhaust available connections if new ones are opened too rapidly or closed too soon. Consider increasing the idle connection wait time to give the server more time to reclaim connections:

JSONCopied
{
  "Connection Timeout": 30,
  "Delay Closing Idle Connection": 30
}

2. Verify Credential & Tunnel Configuration

If you’re using an SSH tunnel (or other advanced options) to connect to your Postgres server, double-check that your settings are correct. (Note that the Agent node does not support SSH tunnels.) Misconfigured SSH details may result in intermittent connection issues. Ensure the Host, Port, and any tunnel options are set up as expected.

3. Consider Query Batching

In the Postgres node, the way queries are batched can affect how often new connections are made. Options include:

• Single Query – A single query for all items.
• Independently – One query per input item.
• Transaction – All queries executed in a transaction.

Using Single Query or Transaction modes may help reuse a connection for multiple operations instead of opening a new connection each time. Adjusting this setting could alleviate the pressure on your Postgres server.

4. Check Postgres Server Limits

If many connections are opened concurrently (or not reused efficiently), the Postgres server itself may begin to refuse new ones. Review your Postgres server settings (such as maximum allowed connections) to ensure they meet your workload requirements.

5. Reach Out to n8n Cloud Support

Since you’re running n8n on n8n Cloud, if the above adjustments don’t resolve the issue, it might be worth reaching out to n8n Cloud Support. They can offer further guidance or configuration adjustments tailored for the cloud environment.

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By tuning connection reuse parameters and reviewing credential settings along with Postgres server limits, you may resolve the intermittent connection refused error during loops.