gatsbyjs/gatsby · error

Slices are disabled.

Error message

Slices are disabled.

What it means

Thrown by the <Slice> component when process.env.GATSBY_SLICES is falsy at build/runtime. This environment variable gates the entire Slices feature; when it is not enabled, the <Slice> component refuses to render. This is the top-level feature gate — using <Slice> without enabling the feature always fails.

Source

Thrown at packages/gatsby/cache-dir/slice.js:64

      // just in case generating additional contextual information fails, we still want the base message to show
      // and not show another cryptic error message
      try {
        additionalContextMessage = `\n\nSlice component "${slicesContext.sliceRoot.name}" (${slicesContext.sliceRoot.componentPath}) tried to render <Slice alias="${props.alias}"/>`
      } catch {
        // don't need to handle it, we will just skip the additional context message if we fail to generate it
      }

      throw new Error(
        `Nested slices are not supported.${additionalContextMessage}\n\nSee https://gatsbyjs.com/docs/reference/built-in-components/gatsby-slice#nested-slices`
      )
    } else {
      throw new Error(
        `Slice context "${slicesContext.renderEnvironment}" is not supported.`
      )
    }
  } else {
    throw new Error(`Slices are disabled.`)
  }
}

class SlicePropsError extends Error {
  constructor(inBrowser, sliceName, propErrors, renderedByLocation) {
    const errors = Object.entries(propErrors)
      .map(
        ([key, value]) =>
          `not serializable "${value}" type passed to "${key}" prop`
      )
      .join(`, `)

    const name = `SlicePropsError`
    let stack = ``
    let message = ``

    if (inBrowser) {
      let fullStack = ``

View on GitHub (pinned to 8b06340921)

Solutions

1. Set GATSBY_SLICES=true in your environment (e.g. .env.development, .env.production, or CI environment variables) before building.
2. If you don't intend to use Slices, remove the <Slice> component usage from your code.
3. Ensure the env var is available at build time — Gatsby reads it during `gatsby build` / `gatsby develop`.

Example fix

# before — GATSBY_SLICLES not set, using <Slice>
# .env.development
# (missing GATSBY_SLICES)

# after
# .env.development
GATSBY_SLICES=true

// Check feature flag before using Slice
function isSlicesEnabled() {
  return process.env.GATSBY_SLICES === 'true' || process.env.GATSBY_SLICES === true
}

if (isSlicesEnabled()) {
  // safe to use <Slice>
} else {
  console.warn('Slices are disabled. Set GATSBY_SLICES=true to enable.')
}

When it happens

Trigger: A page or component renders <Slice alias='...' />, but the GATSBY_SLICES environment variable is not set (or set to a falsy value) during build. The Slice component's top-level if check fails and throws immediately.

Common situations: Developer copies a <Slice> usage from docs or another project without enabling the feature, the GATSBY_SLICES env var was set in one environment (local) but not another (CI/production), or the feature flag was removed in a Gatsby downgrade.

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AI-assisted analysis of gatsbyjs/gatsby@8b06340921 (2026-08-13). Data as JSON: /api/errors/9ab8b15a7a2e4b7c. Report an issue: GitHub.