FlowiseAI/Flowise · error · Error

Failed to load file ${filePath} using unstructured loader.

Error message

Failed to load file ${filePath} using unstructured loader.

What it means

Thrown when the S3File document loader cannot parse a downloaded S3 object via the Unstructured API. The try block wraps UnstructuredLoader construction, document fetching, metadata handling, and output shaping; any failure inside it is swallowed and rethrown as this generic message. Because the original error is discarded by a bare `catch {}`, the real cause (bad API key, network timeout, unsupported file content, malformed partition response) is invisible to the caller.

Source

Thrown at packages/components/nodes/documentloaders/S3File/S3File.ts:817

                        ocrLanguages,
                        xmlKeepTags,
                        multiPageSections,
                        combineUnderNChars,
                        newAfterNChars,
                        maxCharacters
                    }

                    if (unstructuredAPIKey) obj.apiKey = unstructuredAPIKey

                    const unstructuredLoader = new UnstructuredLoader(filePath, obj)

                    let docs = await handleDocumentLoaderDocuments(unstructuredLoader)

                    docs = handleDocumentLoaderMetadata(docs, _omitMetadataKeys, metadata, sourceIdKey)

                    return handleDocumentLoaderOutput(docs, output)
                } catch {
                    throw new Error(`Failed to load file ${filePath} using unstructured loader.`)
                }
            } finally {
                fsDefault.rmSync(tempDir, { recursive: true, force: true })
            }
        }

        return loader.load()
    }

    private getMimeTypeFromExtension(fileName: string): string {
        const extension = path.extname(fileName).toLowerCase()
        const mimeTypeMap: { [key: string]: string } = {
            '.pdf': 'application/pdf',
            '.docx': 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
            '.doc': 'application/msword',
            '.xlsx': 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
            '.xls': 'application/vnd.ms-excel',
            '.pptx': 'application/vnd.openxmlformats-officedocument.presentationml.presentation',

View on GitHub (pinned to abe4a8601a)

Solutions

1. Check the Unstructured API URL and key in the node inputs and verify the endpoint is reachable with a curl POST.
2. Temporarily replace the bare `catch {}` with `catch (e) { throw new Error('...: ' + e.message) }` to surface the root cause, then revert.
3. Verify the downloaded temp file at filePath is non-empty and openable before calling the loader.
4. Confirm the file type is supported by your Unstructured version and that the file is not password-protected.
5. Increase request timeouts or retry with backoff if the failure is intermittent.

Example fix

// before
} catch {
    throw new Error(`Failed to load file ${filePath} using unstructured loader.`)
}

// after
} catch (e: any) {
    throw new Error(`Failed to load file ${filePath} using unstructured loader: ${e?.message ?? e}`)
}

// Before calling the loader, verify the file exists and the API is reachable
import fs from 'fs'
if (!fs.existsSync(filePath) || fs.statSync(filePath).size === 0) {
    throw new Error(`Cannot load: temp file missing or empty at ${filePath}`)
}
const url = new URL(unstructuredAPIUrl) // throws on malformed URL
// optionally HEAD the endpoint

function isUnstructuredConfig(v: unknown): v is { apiUrl: string; apiKey?: string } {
    if (typeof v !== 'object' || v === null) return false
    const o = v as any
    return typeof o.apiUrl === 'string' && /^https?:\/\//.test(o.apiUrl)
}

try {
    return await handleDocumentLoaderOutput(docs, output)
} catch (e: any) {
    // preserve root cause for upstream handling
    throw new Error(`Unstructured load failed for ${filePath}: ${e?.message ?? e}`, { cause: e })
}

When it happens

Trigger: Initiating an S3File load with the Unstructured loader path selected (unstructuredAPIUrl configured), where the downloaded file fails to partition. This happens when the Unstructured API URL is unreachable/wrong, the API key is missing or rejected, the file content is corrupt or password-protected, the temp file write at filePath fails, or the partition response is non-array.

Common situations: Misconfigured UNSTRUCTURED_API_URL pointing to a deleted/local instance, expired or empty unstructuredAPIKey, very large files exceeding the API timeout, transient network blips to the Unstructured service, or a file extension that the mime map accepts but Unstructured itself cannot partition.

Related errors

• Failed to process binary file: ${error.message}
• Failed to fetch ${url}: ${error}
• Failed to load S3 document: ${error.message}
• Unsupported binary file type: ${mimeType}
• Failed to partition file with error ${response.status} and m

AI-assisted analysis of FlowiseAI/Flowise@abe4a8601a (2026-08-12). Data as JSON: /api/errors/27eaeb27fb589955. Report an issue: GitHub.