janhq/jan · warning

TOO_LARGE

Error message

TOO_LARGE

What it means

The preview loader enforces MAX_PREVIEW_BYTES twice: once via the content-length header before reading, once on the decoded text length. Exceeding either throws new Error(TOO_LARGE), which the panel renders as a 'file too large to preview' state instead of loading the content.

Solutions

1. Choose a different preview mode (e.g. open externally) for large files.
2. Increase MAX_PREVIEW_BYTES if legitimately larger text previews are needed.
3. Range-request only the first N bytes for a truncated preview.
4. Fix kind detection so binaries don't enter the text preview path.

Example fix

// before
if (size > MAX_PREVIEW_BYTES) throw new Error(TOO_LARGE)
// after
if (size > MAX_PREVIEW_BYTES) {
  throw new Error(`${TOO_LARGE} (${size} > ${MAX_PREVIEW_BYTES} bytes)`)
}

const head = await fetch(url, { method: 'HEAD' })
const size = Number(head.headers.get('content-length') ?? 0)
if (head.ok && size > MAX_PREVIEW_BYTES) {
  return { status: 'too-large' }
}

const isPreviewableSize = (size: number): boolean =>
  Number.isFinite(size) && size > 0 && size <= MAX_PREVIEW_BYTES

try {
  const content = await loadPreview(url)
  setState({ status: 'ready', content })
} catch (err) {
  if (err.message === TOO_LARGE) {
    setState({ status: 'too-large' })
  } else {
    setState({ status: 'error', message: err.message })
  }
}

When it happens

Trigger: Opening a text preview for a file whose content-length header exceeds MAX_PREVIEW_BYTES, or whose decoded body is longer than the limit (e.g. large log, dataset, or binary file misdetected as text).

Common situations: Clicking a preview on multi-hundred-MB data files; content-length missing so the limit is only caught after downloading the whole body; binary assets routed into the text preview path.

Understand the failure class

Background: "File too large" / "file size exceeds limit" errors: why libraries cap file sizes and how to fix them — this error's family across 46 libraries.

Related errors

• ${res.status}

AI-assisted analysis of janhq/jan@7205d770c1 (2026-09-17). Data as JSON: /api/errors/bf45449b87365d73. Report an issue: GitHub.

Appendix: source

Thrown at web-app/src/containers/CoworkPreviewPanel.tsx:109

    if (kind === 'file') {
      setState({ status: 'unsupported', path })
      return
    }
    setState({ status: 'loading', path })

    void (async () => {
      const url = getServiceHub().core().convertFileSrc(abs)
      if (isAssetKind(kind)) {
        // The element streams the file itself, so there is nothing to fetch and
        // a large video costs nothing to "open".
        if (alive) setState({ status: 'ready', path, kind, assetUrl: url })
        return
      }
      try {
        const res = await fetch(url)
        if (!res.ok) throw new Error(String(res.status))
        const size = Number(res.headers.get('content-length') ?? 0)
        if (size > MAX_PREVIEW_BYTES) throw new Error(TOO_LARGE)
        const content = await res.text()
        if (content.length > MAX_PREVIEW_BYTES) throw new Error(TOO_LARGE)
        if (!alive) return
        setState({
          status: 'ready',
          path,
          kind,
          content,
          unresolvedRefs: kind === 'html' ? unresolvedRefs(content) : undefined,
          externalRefs: kind === 'html' ? externalRefs(content) : undefined,
        })
      } catch (e) {
        if (!alive) return
        setState({
          status: 'failed',
          path,
          reason: e instanceof Error ? e.message : String(e),
        })

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