FlowiseAI/Flowise · error · Error

Failed to load fs/promises. Make sure you are running in Nod

Error message

Failed to load fs/promises. Make sure you are running in Node.js environment.

What it means

Thrown by TextLoader.imports() in Jsonlines.ts when import('node:fs/promises') rejects. Identical cause to Json.ts: the Node fs built-in is unavailable in the current runtime or stripped by a bundler.

Source

Thrown at packages/components/nodes/documentloaders/Jsonlines/Jsonlines.ts:290

                        ? { ...metadata, ...additionalMetadata }
                        : {
                              ...metadata,
                              line: i + 1,
                              ...additionalMetadata
                          }
            })
        })
    }

    static async imports(): Promise<{
        readFile: typeof ReadFileT
    }> {
        try {
            const { readFile } = await import('node:fs/promises')
            return { readFile }
        } catch (e) {
            console.error(e)
            throw new Error(`Failed to load fs/promises. Make sure you are running in Node.js environment.`)
        }
    }
}

class JSONLinesLoader extends TextLoader {
    metadata?: ICommonObject
    additionalMetadata: ICommonObject[] = []

    constructor(filePathOrBlob: string | Blob, public pointer: string, metadata?: any) {
        super(filePathOrBlob)
        if (metadata) {
            this.metadata = typeof metadata === 'object' ? metadata : JSON.parse(metadata)
        }
    }

    async getAdditionalMetadata(): Promise<ICommonObject[]> {
        return this.additionalMetadata
    }

View on GitHub (pinned to abe4a8601a)

Solutions

Run on Node >= 16, or pass a Blob instead of a file path to skip the fs branch.
Mark node:fs/promises as external in the bundler.
Upgrade Node.js.
Use the Blob input path for non-Node runtimes.

Example fix

// before
new JSONLinesLoader('/data/log.jsonl', '/msg')
// after
const blob = new Blob([text], { type: 'application/x-ndjson' })
new JSONLinesLoader(blob, '/msg')

Defensive patterns

Strategy: validation

Validate before calling

function isNodeFsAvailable() {
  try { require.resolve('node:fs/promises'); return true } catch { return false }
}

Type guard

function isBlob(v) { return typeof Blob !== 'undefined' && v instanceof Blob }

Try / catch

try {
  return await jsonLinesLoader.imports()
} catch (e) {
  if (/Failed to load fs\/promises/.test(e.message)) {
    throw new Error('Use Node.js or pass a Blob', { cause: e })
  }
  throw e
}

Prevention

Pass a Blob for non-Node runtimes.
Mark node:fs/promises external in bundler config.
Run on Node >= 16.
Confirm runtime before file-path input.

When it happens

Trigger: Browser/edge runtime without node:fs/promises; bundler not marking the module external; Node < 16; ESM/CJS interop dropping the node: scheme.

Common situations: Serverless browser runtime; misconfigured webpack/rollup/esbuild; corrupted Node install; old Node version.

Related errors

AI-assisted analysis of FlowiseAI/Flowise@abe4a8601a (2026-08-12). Data as JSON: /api/errors/e0d0d278ca8194e1. Report an issue: GitHub.