gatsbyjs/gatsby · error · Error

You've passed something other than string to the exclude…

Error message

You've passed something other than string to the exclude array. This is supported, but you'll have to write a custom filter function.
Ignoring the input for now: ${JSON.stringify(excludedRoute, null, 2)}
https://www.gatsbyjs.com/plugins/gatsby-plugin-sitemap/#api-reference
      

What it means

gatsby-plugin-sitemap's defaultFilterPages applies each entry of the `exclude` option against page URLs via minimatch. The default implementation only handles string entries (glob patterns). If an entry is not a string (a RegExp, function, object, or number), it throws and points the user to the API reference to supply a custom `filterPages` function instead. The message says non-string entries are 'supported' only via a custom filter, not via the default.

Solutions

1. Convert RegExp excludes to minimatch glob strings, e.g. use '/draft/**' instead of /\/draft\//.
2. If you need RegExp/function logic, provide a custom options.filterPages function and do the matching yourself.
3. Ensure every element of the exclude array is a string when using the default filter.

Example fix

// before
{
  resolve: `gatsby-plugin-sitemap`,
  options: { exclude: [`/secret`, /\?lang=/] }
}

// after (glob string)
{
  resolve: `gatsby-plugin-sitemap`,
  options: { exclude: [`/secret`, `/*?lang=*`] }
}
// or custom filter for regex logic
options: { filterPages: (page, excludedRoutes) => excludedRoutes.every(...) }

function normalizeExcludes(exclude) {
  const arr = Array.isArray(exclude) ? exclude : [];
  const bad = arr.filter(e => typeof e !== 'string');
  if (bad.length) {
    throw new Error('gatsby-plugin-sitemap exclude entries must be strings; ' +
      'use a custom filterPages for RegExp/function logic.');
  }
  return arr;
}

function isStringArray(arr) {
  return Array.isArray(arr) && arr.every(e => typeof e === 'string');
}

When it happens

Trigger: Configuring the plugin with options.exclude containing a RegExp (e.g. /\/draft\//), a function, an object, or any non-string, e.g. { resolve: 'gatsby-plugin-sitemap', options: { exclude: ['/secret', /\?lang=/] } }.

Common situations: Wanting regex exclusion (common need) and assuming the default filter accepts RegExp; migrating from another sitemap plugin that allowed functions; passing an object like { path: '/x' } by mistake.

Related errors

• Invalid options passed to page Filter function
• createNode must be a function, was
• createNodeId must be a function, was
• Neither "cache" or "getCache" was passed. getCache must be…
• Neither "cache" or "getCache" was passed. getCache must be…

AI-assisted analysis of gatsbyjs/gatsby@8b06340921 (2026-08-13). Data as JSON: /api/errors/34948fb4ca9f6048. Report an issue: GitHub.

Appendix: source

Thrown at packages/gatsby-plugin-sitemap/src/internals.js:110

 *
 * This allows filtering any data in any way.
 *
 * This Function is executed via allPages.filter((page) => !excludes.some((excludedRoute) => thisFunc(page, ecludedRoute, tools)))
 * allPages is the results of the resolvePages
 *
 * @param {object} page
 * @param {string} excludedRoute - Array from plugin config `options.exclude`
 * @param {object} tools - contains required tools for filtering
 *
 * @returns {boolean}
 */
export function defaultFilterPages(
  page,
  excludedRoute,
  { minimatch, withoutTrailingSlash, resolvePagePath }
) {
  if (typeof excludedRoute !== `string`) {
    throw new Error(
      `You've passed something other than string to the exclude array. This is supported, but you'll have to write a custom filter function.
Ignoring the input for now: ${JSON.stringify(excludedRoute, null, 2)}
https://www.gatsbyjs.com/plugins/gatsby-plugin-sitemap/#api-reference
      `
    )
  }

  // Minimatch is always scary without an example
  // TODO add example
  return minimatch(
    withoutTrailingSlash(resolvePagePath(page)),
    withoutTrailingSlash(excludedRoute)
  )
}

/**
 * @name serialize
 *

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