Queries cannot be run directly on a session with an open transaction; either run from within the transaction or use a different session.

[taasan]

Bug Report

Trying to run multiple queries on a session with Promise.all fails.

Session docs say:

A Session instance is used for handling the connection and sending queries through the connection. In a single session, multiple queries will be executed serially. In order to execute parallel queries, multiple sessions are required.

FWIW I'm not trying to execute the queries in parallel, this is just a minimal reproduction of an error in a large codebase when upgrading driver from v1.4.x to 6.x, it works on v1.4.x.

The driver throws an error saying I can't run queries on a session with an open transaction, but I don't have an open transaction.

The promise is rejected at

neo4j-javascript-driver/packages/core/src/session.ts

Line 278 in 2ff063c

resultPromise = Promise.reject(

To reproduce

import neo4j from "neo4j-driver";

const driver = neo4j.driver("neo4j://localhost");
const session = driver.session();
const runQuery = () => session.run("RETURN 1;");

await Promise.all([runQuery(), runQuery()]);

> node index.js

node:internal/modules/run_main:123
    triggerUncaughtException(
    ^

Neo4jError: Queries cannot be run directly on a session with an open transaction; either run from within the transaction or use a different session.

    at captureStacktrace (/home/dev/node_modules/neo4j-driver-core/lib/result.js:101:17)
    at Result.GenericResult (/home/dev/node_modules/neo4j-driver-core/lib/result.js:141:23)
    at new Result (/home/dev/node_modules/neo4j-driver-core/lib/result.js:711:42)
    at Session._run (/home/dev/node_modules/neo4j-driver-core/lib/session.js:224:16)
    at Session.run (/home/dev/node_modules/neo4j-driver-core/lib/session.js:188:27)
    at runQuery (file:///home/dev/index.js:5:32)
    at file:///home/dev/index.js:7:32
    at ModuleJob.run (node:internal/modules/esm/module_job:345:25)
    at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:665:26)
    at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:117:5) {
  constructor: [Function: Neo4jError] {
    isRetriable: [Function (anonymous)],
    isRetryable: [Function (anonymous)]
  },
  cause: undefined,
  gqlStatus: '50N42',
  gqlStatusDescription: 'error: general processing exception - unexpected error. Queries cannot be run directly on a session with an open transaction; either run from within the transaction or use a different session.',
  diagnosticRecord: { OPERATION: '', OPERATION_CODE: '0', CURRENT_SCHEMA: '/' },
  classification: 'UNKNOWN',
  rawClassification: undefined,
  code: 'N/A',
  retriable: false,
  retryable: false
}

Node.js v22.20.0

My Environment

Javascript Runtime Version: v22.20.0, v24.4.1
Driver Version: 6.0.1
Neo4j Version and Edition: 5.26.10
Operating System: Fedora 43

[MaxAake]

Hello @taasan

Effectively your code is trying to run these queries in parallel. Sessions do not have a queue of pending queries, so you need to ensure that your previous query is complete (by awaiting the promise from session.run()) before calling the next one.

Because you are not awaiting each call to runQuery() before starting the next, the session is being asked to run another query before it has completed the previous one.

This is not considered a bug, but rather the intended behavior of the driver.

[taasan]

OK. It would be nice with a more correct error message since I don't have an open transaction in the session.

[taasan]

Our code is quite a mess so my example may not be representative, will see what I can figure out.

[MaxAake]

@taasan I think you're right about the error message being confusing. session.run() does execute an auto-commit transaction on the server side, but that isn't language that is used much in driver documentation, so I'll have a look at updating the error message.