Uncaught Exception When Terminating Query by PID – server conn crashed? Error

[iikareem]

Hi Neon team,

We are currently implementing a service that allows the frontend to cancel long-running queries by calling an API endpoint that terminates the query using its PostgreSQL PID (via pg_terminate_backend). However, we consistently encounter an uncaught exception from the Neon client when this happens.

❗ Problem
Whenever the query is forcefully terminated using pg_terminate_backend, we receive the following error from the Neon client library:

Uncaught Exception: error: server conn crashed? at bn.parseErrorMessage (C:\Users\xxx\Documents\GitHub\project\node_modules\@neondatabase\serverless\index.js:949:41) at bn.handlePacket (C:\Users\xxx\Documents\GitHub\project\node_modules\@neondatabase\serverless\index.js:917:75) at bn.parse (C:\Users\xxx\Documents\GitHub\project\node_modules\@neondatabase\serverless\index.js:905:36) at S.<anonymous> (C:\Users\xxx\Documents\GitHub\project\node_modules\@neondatabase\serverless\index.js:956:16) at S.emit (C:\Users\xxx\Documents\GitHub\project\node_modules\@neondatabase\serverless\index.js:316:79) at WebSocket.<anonymous> (C:\Users\xxx\Documents\GitHub\project\node_modules\@neondatabase\serverless\index.js:398:19)

Context :
We are using the @neondatabase/serverless package to connect to our Neon PostgreSQL database.

When the frontend decides that a query is no longer needed (e.g. the user navigates away), it sends a request to our backend to terminate the running query.

The backend issues a SELECT pg_terminate_backend() against the database.

Immediately after that, the Neon client throws an uncaught error and crashes the Node.js process.

🛠️ Expected Behavior
We expect the client to gracefully handle the server-side termination of a query (via pg_terminate_backend) and return a structured error, rather than crashing the process.

✅ Reproduction Steps
Start a long-running query via a Node.js backend using @neondatabase/serverless.

From another request (e.g. triggered by the frontend), call pg_terminate_backend() on that query.

Observe the uncaught exception and stack trace in the Node.js server logs.

📦 Environment

@neondatabase/serverless version: 1.0.0

Node.js version: 24.0.0

Platform: Windows 11

Neon DB: Serverless

🙏 Request
It would be great if the Neon client could catch and properly handle this error scenario, ideally exposing a clear error message that the query was terminated, instead of throwing an uncaught exception.

Thanks in advance!

[jawj]

Sorry for the delayed reply. I've done a bit of playing around but have not yet managed to reproduce this issue.

It would be really helpful to see a brief reproduction in code form.

Amongst other things, this will help clarify whether you're using Client or Pool (WebSocket) or neon (http) for both the cancelled and cancelling connections, and which connection then throws the error.