FlowiseAI/Flowise · error · Error

Failed to load file 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.

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
• Failed to fetch
• Failed to load S3 document
• Failed to partition file with error
• Unsupported binary file type

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

Appendix: 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',

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