{"record":{"id":"ac9b568502366c52","repo":"payloadcms/payload","slug":"could-not-read-uploaded-file-for-type-detection","errorCode":null,"errorMessage":"Could not read uploaded file for type detection.","messagePattern":"Could not read uploaded file for type detection\\.","errorType":"validation","errorClass":"ValidationError","httpStatus":400,"severity":"error","filePath":"packages/payload/src/uploads/checkFileRestrictions.ts","lineNumber":143,"sourceCode":"      _fileBuffer = await fs.readFile(tempFilePath)\n      return _fileBuffer\n    } catch {\n      throw new ValidationError({\n        errors: [{ message: 'Could not read uploaded file for validation.', path: 'file' }],\n      })\n    }\n  }\n\n  // Secondary mimetype check to assess file type from buffer\n  if (configMimeTypes.length > 0) {\n    let detected\n    try {\n      detected =\n        isTempFile && tempFilePath\n          ? await fileTypeFromFile(tempFilePath)\n          : await fileTypeFromBuffer(file.data)\n    } catch {\n      throw new ValidationError({\n        errors: [{ message: 'Could not read uploaded file for type detection.', path: 'file' }],\n      })\n    }\n    const typeFromExtension = file.name.split('.').pop() || ''\n\n    // Handle SVG files that are detected as XML due to <?xml declarations\n    if (\n      detected?.mime === 'application/xml' &&\n      configMimeTypes.some(\n        (type) => type.includes('image/') && (type.includes('svg') || type === 'image/*'),\n      )\n    ) {\n      const isSvg = detectSvgFromXml(await getFileBuffer())\n      if (isSvg) {\n        detected = { ext: 'svg', mime: 'image/svg+xml' }\n      }\n    }\n","sourceCodeStart":125,"sourceCodeEnd":161,"githubUrl":"https://github.com/payloadcms/payload/blob/00c58b35c0ed348ddc22daabf467b139727214fd/packages/payload/src/uploads/checkFileRestrictions.ts#L125-L161","documentation":"Thrown when the file-type library's fileTypeFromFile(tempFilePath) or fileTypeFromBuffer(file.data) throws synchronously during the secondary mimetype-detection step (it is wrapped in try/catch). Note this is distinct from the library returning undefined/null (undetectable), which is handled gracefully — this fires only when the call actively rejects.","triggerScenarios":"fileTypeFromFile rejects because the temp path is unreadable, or fileTypeFromBuffer rejects because file.data is not a valid Buffer/Uint8Array (e.g. undefined, or a truncated stream). Reached only when upload.mimeTypes is configured and checkFileContents is true.","commonSituations":"File buffer was mutated/cleared by middleware before validation; temp file deleted between the existence check and the file-type read; a streaming parser that didn't fully buffer the data; version mismatch in file-type expecting a Buffer but receiving a TypedArray view.","solutions":["Confirm file.data is a populated Buffer for in-memory uploads, or tempFilePath exists for on-disk uploads, before invoking the upload pipeline.","Ensure no middleware mutates or nulls file.data between multipart parse and checkFileRestrictions.","Stabilize the temp directory so it survives the request (see error 241).","If the error is intermittent, log the underlying cause by temporarily replacing the catch with a rethrow to inspect the file-type error."],"exampleFix":"// before\nconst detected = await fileTypeFromBuffer(file.data)\n// after — coerce to a valid Buffer and guard\nif (!Buffer.isBuffer(file.data) || file.data.length === 0) {\n  throw new Error('Empty file buffer; re-upload the file.')\n}\nconst detected = await fileTypeFromBuffer(file.data)","handlingStrategy":"validation","validationCode":"import { Buffer } from 'buffer'\nfunction bufferOk(b: unknown): b is Buffer {\n  return Buffer.isBuffer(b) && (b as Buffer).length > 0\n}\n// before validation:\nif (!bufferOk(file.data) && !file.tempFilePath) throw new Error('No file content to detect')","typeGuard":"const isNonEmptyBuffer = (b: unknown): b is Buffer =>\n  Buffer.isBuffer(b) && b.length > 0","tryCatchPattern":"try {\n  await payload.create({ collection: 'media', file })\n} catch (e) {\n  if (e instanceof ValidationError && /Could not read uploaded file for type detection/.test(e.message)) {\n    notifyOps('file-type detection failed; check temp file lifecycle')\n    askUserToRetry()\n  } else throw e\n}","preventionTips":["Avoid middleware that clears file.data after multipart parsing.","Pin a compatible file-type version.","Ensure tempFilePath is absolute and stable.","Log file.data length and tempFilePath in your upload middleware for diagnosis."],"tags":["upload","validation","file-type","buffer"],"backgroundTag":null,"analyzedSha":"00c58b35c0ed348ddc22daabf467b139727214fd","analyzedAt":"2026-08-12T20:45:03.758Z","schemaVersion":2},"datasetVersion":"2026-08-12T23:17:12.415Z"}