What causes "${REPORTER_PREFIX} Error in default page filter" in gatsbyjs/gatsby?

Inspect the allPages array in your gatsby-node to verify every page has a valid `path` string before sitemap generation runs.

gatsbyjs/gatsby · error · Error

Error in default page filter

Error message

${REPORTER_PREFIX} Error in default page filter

What it means

Thrown by gatsby-plugin-sitemap's page filtering logic when the internal default page filter function throws an exception while testing a page against a default exclude pattern. The catch block wraps any underlying error from defaultFilterPages, minimatch, or path resolution utilities into this generic message, discarding the original error's details.

Solutions

Inspect the allPages array in your gatsby-node to verify every page has a valid `path` string before sitemap generation runs.
Check Gatsby and gatsby-plugin-sitemap versions are compatible (run `npm ls gatsby gatsby-plugin-sitemap`).
Temporarily add logging before the filter to dump page objects that lack a path field to identify the offending source plugin.
If using a custom createPage call, ensure each page is created with a non-empty string path.

Example fix

// before
createPage({ path: '', component: ... })
// after
createPage({ path: '/valid-path/', component: ... })

Defensive patterns

Strategy: validation

Validate before calling

// Before calling pageFilter, ensure all pages have valid paths
const validPages = allPages.filter(page => typeof page?.path === 'string' && page.path.length > 0)
if (validPages.length !== allPages.length) {
  console.warn(`${allPages.length - validPages.length} pages have invalid paths`)
}
pageFilter({ allPages: validPages, filterPages, excludes })

Type guard

const hasValidPath = (page: unknown): page is { path: string } =>
  typeof page === 'object' && page !== null && typeof (page as any).path === 'string' && (page as any).path.length > 0

Prevention

Validate page objects from source plugins have a non-empty string path field before sitemap generation.
Run integration tests that assert every page created via createPage has a valid path.
Log page shapes during development to catch malformed nodes early.

When it happens

Trigger: The defaultExcludes.some() loop calls defaultFilterPages() for every page; if the page object lacks expected properties (e.g., path is undefined), or if withoutTrailingSlash/resolvePagePath receive malformed input, the inner call throws and is caught by the bare `catch {}` which rethrows this generic message.

Common situations: Pages created by other plugins that have a non-standard shape (missing or null path field), corrupted page nodes from a source plugin, or a Gatsby version mismatch where the page object schema changed.

Related errors

AI-assisted analysis of gatsbyjs/gatsby@8b06340921 (2026-08-13). Data as JSON: /api/errors/54f79851394b4dd7. Report an issue: GitHub.

Appendix: source

Thrown at packages/gatsby-plugin-sitemap/src/internals.js:174

    typeof filterPages !== `function` ||
    !Array.isArray(excludes)
  ) {
    throw new Error(`Invalid options passed to page Filter function`)
  }

  // TODO we should optimize these loops
  const filteredPages = allPages.filter(page => {
    const defaultFilterMatches = defaultExcludes.some(exclude => {
      try {
        const doesMatch = defaultFilterPages(page, exclude, {
          minimatch,
          withoutTrailingSlash,
          resolvePagePath,
        })

        return doesMatch
      } catch {
        throw new Error(`${REPORTER_PREFIX} Error in default page filter`)
      }
    })

    if (defaultFilterMatches) {
      messages.push(
        `${REPORTER_PREFIX} Default filter excluded page ${resolvePagePath(
          page
        )}`
      )
    }

    // If page is marked to be excluded via defaults there's no need to check page for custom excludes
    if (defaultFilterMatches) {
      return !defaultFilterMatches
    }

    const customFilterMatches = excludes.some(exclude => {
      try {

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