Budibase/budibase · error

Unable to retrieve CSV - invalid stream

Error message

Unable to retrieve CSV - invalid stream

What it means

readCsv in the S3 integration validates that the GetObject response body can be transformed into a Node.js Readable stream before parsing CSV. If response.Body is undefined or the transformToWebStream() result is not a stream.Readable, there is nothing to pipe the CSV from, so the integration throws this error instead of failing obscurely downstream.

Source

Thrown at packages/server/src/integrations/s3.ts:256

      Bucket: query.bucket,
      Delimiter: query.delimiter,
      Marker: query.marker,
      MaxKeys: query.maxKeys,
      Prefix: query.prefix,
    })
    return response.Contents
  }

  async readCsv(query: { bucket: string; key: string }) {
    const response = await this.client.getObject({
      Bucket: query.bucket,
      Key: query.key,
    })

    const fileStream = response.Body?.transformToWebStream()

    if (!fileStream || !(fileStream instanceof stream.Readable)) {
      throw new Error("Unable to retrieve CSV - invalid stream")
    }

    let csvError = false
    return new Promise((resolve, reject) => {
      fileStream.on("error", (err: Error) => {
        reject(err)
      })
      const response = csv()
        .fromStream(fileStream)
        .on("error", () => {
          csvError = true
        })
      fileStream.on("end", () => {
        resolve(response)
      })
    }).catch(err => {
      if (csvError) {
        throw new Error("Could not read CSV")

View on GitHub (pinned to a81a902e9a)

Solutions

1. Verify the object exists at the configured bucket/key (aws s3 ls s3://<bucket>/<key>) and that the key is correct in the query.
2. Check the S3 integration credentials/permissions have s3:GetObject on the object.
3. Ensure a supported @aws-sdk/client-s3 version is installed where response.Body implements transformToWebStream().
4. If using an S3-compatible store (MinIO etc.), confirm the endpoint returns standard GetObject responses.

Example fix

// before: wrong key, object missing
const query = { bucket: "my-bucket", key: "exports/data.csv" }
// after: verify key exists and credentials have GetObject
aws s3 ls s3://my-bucket/exports/data.csv  # then rerun the query with the confirmed key

import { HeadObjectCommand, S3Client } from "@aws-sdk/client-s3"
const s3 = new S3Client({})
await s3.send(new HeadObjectCommand({ Bucket: query.bucket, Key: query.key })) // throws if missing/no permission

function hasReadableBody(res: { Body?: unknown }): res is { Body: { transformToWebStream(): ReadableStream } } {
  return !!res.Body && typeof (res.Body as any).transformToWebStream === "function"
}

try {
  const csv = await s3Integration.readCsv(query)
} catch (err) {
  if (err instanceof Error && err.message === "Unable to retrieve CSV - invalid stream") {
    // check bucket/key/permissions, then retry or surface config error
  } else { throw err }
}

When it happens

Trigger: Calling the S3 read CSV query where GetObject returns no Body (object missing/deleted, no read permission yielding a response without body in some SDK paths) or transformToWebStream() returns a non-Readable value (SDK version mismatch, e.g. @aws-sdk/client-s3 v3 with wrong stream wiring).

Common situations: Specifying a wrong bucket/key so the object doesn't exist; IAM credentials lacking s3:GetObject; upgrading or mismatching AWS SDK versions where response.Body type changed; reading from a non-S3-compatible endpoint returning unexpected body types.

Related errors

• Could not read CSV
• Access denied to object store bucket.${err}
• Unable to retrieve stream - invalid response
• Error constructing OIDC refresh strategy: message=${err.mess
• Unable to determine delimiter

AI-assisted analysis of Budibase/budibase@a81a902e9a (2026-08-29). Data as JSON: /api/errors/d98a74977e9bcc79. Report an issue: GitHub.