Error in cloudflare workers : Uncaught (in response) Error: The script will never generate a response

What was reported

Issue neondatabase/serverless#11 (closed, 17 comments): Hi I’m getting the following error in Cloudflare workers

A hanging Promise was canceled. This happens when the worker runtime is waiting for a Promise from JavaScript to resolve, but has detected that the Promise cannot possibly ever resolve because all code and events related to the Promise's I/O context have already finished. ✘ [ERROR] Uncaught (in response) Error: The script will never generate a response.

My code is simple

import { Client } from '@neondatabase/serverless'
import { Env } from './models'

export default {
    async fetch(request: Request, env: Env

## The verified resolution

[jawj (maintainer)]: Do not keep a Pool/Client alive between requests on Cloudflare Workers  -  each invocation is isolated and the worker kills promises tied to a finished request's I/O context ('The script will never generate a response'). Create the Pool inside the fetch/request handler. Same symptom occurs locally when the connection string env var is undefined (put env vars in `.dev.vars` for `wrangler dev`), and newer driver versions surface connect errors more helpfully instead of hanging.

Asked in gh:neondatabase/serverless#11 (https://github.com/neondatabase/serverless/issues/11): Error in cloudflare workers : Uncaught (in response) Error: The script will never generate a response. The issue report: Issue neondatabase/serverless#11 (closed, 17 comments): Hi I’m getting the following error in Cloudflare workers

A hanging Promise was canceled. This happens when the worker runtime is waiting for a Promise from JavaScript to resolve, but has detected that the Promise cannot possibly ever resolve because all code and events related to the Promise's I/O context have already finished. ✘ [ERROR] Uncaught (in response) Error: The script will never generate a response.

My code is simple

import { Client } from '@neondatabase/serverless'
import { Env } from './models'

export default {
    async fetch(request: Request, env: Env The verified answer: [jawj (maintainer)]: Do not keep a Pool/Client alive between requests on Cloudflare Workers  -  each invocation is isolated and the worker kills promises tied to a finished request's I/O context ('The script will never generate a response'). Create the Pool inside the fetch/request handler. Same symptom occurs locally when the connection string env var is undefined (put env vars in `.dev.vars` for `wrangler dev`), and newer driver versions surface connect errors more helpfully instead of hanging.