slidevjs/slidev · error · Error

Slide ${anchorNo} is out of sync with its source file. Try a

Error message

Slide ${anchorNo} is out of sync with its source file. Try again.

What it means

Thrown by moveSlide when md.slides.indexOf(anchor.source) < 0 after the 'from' slide was already spliced out, i.e. the anchor slide's SourceSlideInfo is not in its file's slides array. Same consistency-guard family as the from-side check; indicates the anchor's source object is stale.

Source

Thrown at packages/slidev/node/mcp/operations.ts:200

    throw new Error(
      `Cannot move a slide across markdown files: slide ${from} is in "${slide.source.filepath}" `
      + `but slide ${anchorNo} is in "${anchor.source.filepath}" (imported with \`src:\`). `
      + `Move it within its own file, or edit the \`src:\` imports in the entry file manually.`,
    )
  }

  assertNotEntryHeadmatter(data, slide.source, 'move')
  if (before != null)
    assertNotEntryHeadmatter(data, anchor.source, 'insert a slide before')

  const md = getMarkdown(data, slide.source)
  const fromIdx = md.slides.indexOf(slide.source)
  if (fromIdx < 0)
    throw new Error(`Slide ${from} is out of sync with its source file. Try again.`)
  md.slides.splice(fromIdx, 1)
  const anchorIdx = md.slides.indexOf(anchor.source)
  if (anchorIdx < 0)
    throw new Error(`Slide ${anchorNo} is out of sync with its source file. Try again.`)
  md.slides.splice(before != null ? anchorIdx : anchorIdx + 1, 0, slide.source)
  const fileContent = await parser.save(md)
  return { moved: slide, anchor, filepath: md.filepath, fileContent }
}

View on GitHub (pinned to 0d798ace58)

Solutions

1. Re-fetch data via ctx.getData() right before moveSlide and retry.
2. Confirm the anchor slide still exists via slidev-list-slides before reissuing the move.
3. Prevent concurrent writers on the same markdown file.

Example fix

// before: anchor reference stale after an external edit
const data = await ctx.getData()
await moveSlide(data, { from: 2, before: 5 }) // throws: anchor out of sync

// after: refresh and re-resolve anchor
const data = await ctx.getData()
await moveSlide(data, { from: 2, before: 5 })

function anchorSlideInFile(md: { slides: SourceSlideInfo[] }, source: SourceSlideInfo): boolean {
  return md.slides.indexOf(source) >= 0
}

// before moveSlide, validate the anchor too:
const anchor = resolveSlide(data, before ?? after!)
const md = data.markdownFiles[anchor.source.filepath]
if (!md || !anchorSlideInFile(md, anchor.source)) return // refresh

function anchorSourceCurrent(md: { slides: SourceSlideInfo[] }, s: SourceSlideInfo): s is SourceSlideInfo {
  return md.slides.indexOf(s) >= 0
}

try {
  return await moveSlide(data, opts)
} catch (e) {
  const anchorNo = opts.before ?? opts.after
  if (e instanceof Error && new RegExp(`Slide ${anchorNo} is out of sync`).test(e.message)) {
    data = await ctx.getData()
    return await moveSlide(data, opts)
  }
  throw e
}

When it happens

Trigger: Calling moveSlide where the anchor (before/after) slide's source is no longer a member of md.slides, typically because external edits invalidated the object reference between getData() and the call.

Common situations: Concurrent edits to the anchor's file; stale getData() snapshot; anchor imported via src: from a file that was modified.

Related errors

• Slide ${from} is out of sync with its source file. Try again
• Slide ${no} is out of sync with its source file. Try again.
• Markdown file not loaded: ${source.filepath}
• Specify exactly one of `before` or `after`.
• The `before`/`after` anchor must be a different slide than `

AI-assisted analysis of slidevjs/slidev@0d798ace58 (2026-08-12). Data as JSON: /api/errors/7429547f0af3a06a. Report an issue: GitHub.