linshenkx/prompt-optimizer · error · Error

This PNG file does not contain Prompt Optimizer favorite sha

Error message

This PNG file does not contain Prompt Optimizer favorite share data. Use the original exported PNG file; screenshots or compressed images cannot be imported.

What it means

When given binary input (Uint8Array/ArrayBuffer), readFavoriteSharePackage looks for a tEXt chunk with the favorite-share keyword and throws if none exists. Screenshots, re-encodes, or any process that rewrites PNG data destroy metadata chunks, so only the original exported PNG can be re-imported.

Source

Thrown at packages/ui/src/utils/favorite-share-export.ts:1461

}

export const readFavoriteSharePackage = (
  input: ArrayBuffer | Uint8Array | string,
): Uint8Array => {
  if (typeof input === 'string') {
    const parser = new DOMParser()
    const document = parser.parseFromString(input, 'text/html')
    const script = document.getElementById(FAVORITE_SHARE_HTML_SCRIPT_ID)
    if (!script?.textContent) {
      throw new Error('This HTML file does not contain Prompt Optimizer favorite share data')
    }
    return base64ToBytes(parseSharePayload(script.textContent).packageBase64)
  }

  const bytes = input instanceof Uint8Array ? input : new Uint8Array(input)
  const chunk = readPngTextChunk(bytes, FAVORITE_SHARE_PNG_TEXT_KEYWORD)
  if (!chunk) {
    throw new Error('This PNG file does not contain Prompt Optimizer favorite share data. Use the original exported PNG file; screenshots or compressed images cannot be imported.')
  }
  return base64ToBytes(parseSharePayload(chunk).packageBase64)
}

export const looksLikeFavoriteShareHtml = (
  fileName: string | undefined,
  text: string,
): boolean => {
  const normalizedName = String(fileName || '').toLowerCase()
  return (
    normalizedName.endsWith('.html') ||
    normalizedName.endsWith('.htm') ||
    text.includes(FAVORITE_SHARE_HTML_SCRIPT_ID)
  ) && text.includes(FAVORITE_SHARE_SCHEMA_VERSION)
}

export const looksLikeFavoriteSharePng = (
  fileName: string | undefined,

View on GitHub (pinned to 3e677b1d9f)

Solutions

1. Import the original exported PNG file, not a screenshot or re-shared copy
2. Transfer the file as a file attachment preserving bytes (avoid messenger image compression)
3. Before importing, sniff for the chunk yourself with readPngTextChunk(bytes, FAVORITE_SHARE_PNG_TEXT_KEYWORD) and show a clear message
4. Prefer exporting the HTML share format when the transfer channel re-compresses images

Example fix

// before
const pkg = readFavoriteSharePackage(pngBytes)

// after
const chunk = readPngTextChunk(pngBytes, FAVORITE_SHARE_PNG_TEXT_KEYWORD)
if (!chunk) {
  throw new UserError('No share data in this PNG. Please use the original exported file.')
}
const pkg = readFavoriteSharePackage(pngBytes)

const bytes = new Uint8Array(await file.arrayBuffer())
const hasPayload = readPngTextChunk(bytes, FAVORITE_SHARE_PNG_TEXT_KEYWORD) != null
if (!hasPayload) throw new UserError('Use the original exported PNG; screenshots cannot be imported')

const hasFavoriteShareChunk = (b: Uint8Array): boolean =>
  isPng(b) && readPngTextChunk(b, FAVORITE_SHARE_PNG_TEXT_KEYWORD) != null

try { readFavoriteSharePackage(pngBytes) } catch (e) { if (e.message.includes('screenshots or compressed images')) askForOriginalFile(); else throw e }

When it happens

Trigger: Importing a PNG that was screenshotted, re-saved by an image editor, compressed by a chat app, or re-encoded after upload — all of which drop the tEXt chunk; or importing a PNG that never contained share data.

Common situations: Users send the exported PNG through WhatsApp/Slack/imgur which strips metadata or re-encodes; users take a screenshot of the PNG instead of saving it; image CDN or build pipeline (sharp, squoosh) optimizing away tEXt chunks.

Related errors

• Prompt asset is not available for this favorite
• Invalid import data format
• Import data contains favorite with empty content
• Invalid function mode in import data: functionMode=${functio
• Failed to import favorites: ${errorMessage}

AI-assisted analysis of linshenkx/prompt-optimizer@3e677b1d9f (2026-08-27). Data as JSON: /api/errors/01d9d9a193df9e5f. Report an issue: GitHub.