n8n-io/n8n · critical · DriverPackageNotInstalledError

Postgres package has not been found installed. Try to instal

Error message

Postgres package has not been found installed. Try to install it: npm install pg --save

What it means

DriverPackageNotInstalledError('Postgres', 'pg') is thrown from PostgresDriver.loadDependencies when both this.options.driver is unset and require('pg') throws. The driver cannot operate without the pg client library; this fires during connect() before any real DB work.

Source

Thrown at packages/@n8n/typeorm/src/driver/postgres/PostgresDriver.ts:1324

				`To use streams you should install pg-query-stream package. Please run npm i pg-query-stream --save command.`,
			);
		}
	}

	// -------------------------------------------------------------------------
	// Protected Methods
	// -------------------------------------------------------------------------

	/**
	 * If driver dependency is not given explicitly, then try to load it via "require".
	 */
	protected loadDependencies(): void {
		try {
			const postgres = this.options.driver || require('pg');
			this.postgres = postgres;
		} catch (e) {
			// todo: better error for browser env
			throw new DriverPackageNotInstalledError('Postgres', 'pg');
		}
	}

	/**
	 * Creates a new connection pool for a given database credentials.
	 */
	protected async createPool(
		options: PostgresConnectionOptions,
		credentials: PostgresConnectionCredentialsOptions,
	): Promise<any> {
		const { logger } = this.connection;
		credentials = Object.assign({}, credentials);

		// build connection options for the driver
		// See: https://github.com/brianc/node-postgres/tree/master/packages/pg-pool#create
		const connectionOptions: pg.PoolConfig = {
			connectionString: credentials.url,
			host: credentials.host,

View on GitHub (pinned to 5ac6606e81)

Solutions

Install pg in the package that runs the DataSource: 'npm install pg'.
Pass the driver explicitly via options.driver = pg if installing globally is not possible (this short-circuits the require).
For monorepos, ensure pg is a real dependency of the runtime workspace, not just of a sibling.
Rebuild/reinstall node_modules if a prune step removed it.

Example fix

// before
// DB_TYPE=postgres but pg not installed -> DriverPackageNotInstalledError
// after
npm install pg

Defensive patterns

Strategy: validation

Validate before calling

// At startup, probe that pg is resolvable when postgres is selected.
if (config.dbType === 'postgres') {
  try { require.resolve('pg'); } catch {
    throw new Error('pg package not installed; run npm install pg');
  }
}

Try / catch

import { DriverPackageNotInstalledError } from '@n8n/typeorm';
try {
  await dataSource.initialize();
} catch (e) {
  if (e instanceof DriverPackageNotInstalledError && e.args?.[0] === 'Postgres') {
    failStartup('Postgres driver needs the pg package; run npm install pg');
  }
  throw e;
}

Prevention

Pin pg as a hard dependency in the package that runs the DataSource.
Run a startup probe for the driver package matching DB_TYPE.
In monorepos, ensure pg is hoisted to where the runtime resolves it.
Audit image-pruning scripts so they do not strip pg.

When it happens

Trigger: DB_TYPE=postgres (or options.type='postgres') is configured but the 'pg' npm package is not installed in the running process; or pg is installed in a different workspace/node_modules than the one the process resolves from.

Common situations: Custom Docker image that did not include pg; pnpm hoisting / strict-node-loader setup that hides pg from the typeorm package; an upgrade that moved pg to optionalDependencies and it got pruned.

Related errors

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/9a000656226df307. Report an issue: GitHub.