# Error reference

The following reference is a complete list of the errors you may encounter while using Astro. For additional assistance, including common pitfalls, please also see our [Troubleshooting Guide](/en/guides/troubleshooting/).

## Astro Errors

[Section titled “Astro Errors”](#astro-errors)

* [**UnknownCompilerError**](/en/reference/errors/unknown-compiler-error/)\
  Unknown compiler error.
* [**ClientAddressNotAvailable**](/en/reference/errors/client-address-not-available/)\
  `Astro.clientAddress` is not available in current adapter.
* [**PrerenderClientAddressNotAvailable**](/en/reference/errors/prerender-client-address-not-available/)\
  `Astro.clientAddress` cannot be used inside prerendered routes.
* [**StaticClientAddressNotAvailable**](/en/reference/errors/static-client-address-not-available/)\
  `Astro.clientAddress` is not available in prerendered pages.
* [**NoMatchingStaticPathFound**](/en/reference/errors/no-matching-static-path-found/)\
  No static path found for requested path.
* [**OnlyResponseCanBeReturned**](/en/reference/errors/only-response-can-be-returned/)\
  Invalid type returned by Astro page.
* [**MissingMediaQueryDirective**](/en/reference/errors/missing-media-query-directive/)\
  Missing value for `client:media` directive.
* [**NoMatchingRenderer**](/en/reference/errors/no-matching-renderer/)\
  No matching renderer found.
* [**NoClientEntrypoint**](/en/reference/errors/no-client-entrypoint/)\
  No client entrypoint specified in renderer.
* [**NoClientOnlyHint**](/en/reference/errors/no-client-only-hint/)\
  Missing hint on `client:only` directive.
* [**InvalidGetStaticPathParam**](/en/reference/errors/invalid-get-static-path-param/)\
  Invalid value returned by a `getStaticPaths` path.
* [**InvalidGetStaticPathsEntry**](/en/reference/errors/invalid-get-static-paths-entry/)\
  Invalid entry inside getStaticPath’s return value
* [**InvalidGetStaticPathsReturn**](/en/reference/errors/invalid-get-static-paths-return/)\
  Invalid value returned by getStaticPaths.
* [**GetStaticPathsExpectedParams**](/en/reference/errors/get-static-paths-expected-params/)\
  Missing params property on `getStaticPaths` route.
* [**GetStaticPathsInvalidRouteParam**](/en/reference/errors/get-static-paths-invalid-route-param/)\
  Invalid value for `getStaticPaths` route parameter.
* [**GetStaticPathsRequired**](/en/reference/errors/get-static-paths-required/)\
  `getStaticPaths()` function required for dynamic routes.
* [**ReservedSlotName**](/en/reference/errors/reserved-slot-name/)\
  Invalid slot name.
* [**NoAdapterInstalled**](/en/reference/errors/no-adapter-installed/)\
  Cannot use Server-side Rendering without an adapter.
* [**AdapterSupportOutputMismatch**](/en/reference/errors/adapter-support-output-mismatch/)\
  Adapter does not support server output.
* [**NoAdapterInstalledServerIslands**](/en/reference/errors/no-adapter-installed-server-islands/)\
  Cannot use Server Islands without an adapter.
* [**NoMatchingImport**](/en/reference/errors/no-matching-import/)\
  No import found for component.
* [**InvalidPrerenderExport**](/en/reference/errors/invalid-prerender-export/)\
  Invalid prerender export.
* [**InvalidComponentArgs**](/en/reference/errors/invalid-component-args/)\
  Invalid component arguments.
* [**PageNumberParamNotFound**](/en/reference/errors/page-number-param-not-found/)\
  Page number param not found.
* [**ImageMissingAlt**](/en/reference/errors/image-missing-alt/)\
  Image missing required “alt” property.
* [**InvalidImageService**](/en/reference/errors/invalid-image-service/)\
  Error while loading image service.
* [**MissingImageDimension**](/en/reference/errors/missing-image-dimension/)\
  Missing image dimensions
* [**FailedToFetchRemoteImageDimensions**](/en/reference/errors/failed-to-fetch-remote-image-dimensions/)\
  Failed to retrieve remote image dimensions
* [**UnsupportedImageFormat**](/en/reference/errors/unsupported-image-format/)\
  Unsupported image format
* [**UnsupportedImageConversion**](/en/reference/errors/unsupported-image-conversion/)\
  Unsupported image conversion
* [**PrerenderDynamicEndpointPathCollide**](/en/reference/errors/prerender-dynamic-endpoint-path-collide/)\
  Prerendered dynamic endpoint has path collision.
* [**PrerenderRouteConflict**](/en/reference/errors/prerender-route-conflict/)\
  Prerendered route generates the same path as another route.
* [**ExpectedImage**](/en/reference/errors/expected-image/)\
  Expected src to be an image.
* [**ExpectedImageOptions**](/en/reference/errors/expected-image-options/)\
  Expected image options.
* [**ExpectedNotESMImage**](/en/reference/errors/expected-not-esmimage/)\
  Expected image options, not an ESM-imported image.
* [**IncompatibleDescriptorOptions**](/en/reference/errors/incompatible-descriptor-options/)\
  Cannot set both `densities` and `widths`
* [**ImageNotFound**](/en/reference/errors/image-not-found/)\
  Image not found.
* [**NoImageMetadata**](/en/reference/errors/no-image-metadata/)\
  Could not process image metadata.
* [**CouldNotTransformImage**](/en/reference/errors/could-not-transform-image/)\
  Could not transform image.
* [**ResponseSentError**](/en/reference/errors/response-sent-error/)\
  Unable to set response.
* [**MiddlewareNoDataOrNextCalled**](/en/reference/errors/middleware-no-data-or-next-called/)\
  The middleware didn’t return a `Response`.
* [**MiddlewareNotAResponse**](/en/reference/errors/middleware-not-aresponse/)\
  The middleware returned something that is not a `Response` object.
* [**EndpointDidNotReturnAResponse**](/en/reference/errors/endpoint-did-not-return-aresponse/)\
  The endpoint did not return a `Response`.
* [**LocalsNotAnObject**](/en/reference/errors/locals-not-an-object/)\
  Value assigned to `locals` is not accepted.
* [**LocalsReassigned**](/en/reference/errors/locals-reassigned/)\
  `locals` must not be reassigned.
* [**AstroResponseHeadersReassigned**](/en/reference/errors/astro-response-headers-reassigned/)\
  `Astro.response.headers` must not be reassigned.
* [**MiddlewareCantBeLoaded**](/en/reference/errors/middleware-cant-be-loaded/)\
  Can’t load the middleware.
* [**LocalImageUsedWrongly**](/en/reference/errors/local-image-used-wrongly/)\
  Local images must be imported.
* [**AstroGlobUsedOutside**](/en/reference/errors/astro-glob-used-outside/)\
  Astro.glob() used outside of an Astro file.
* [**AstroGlobNoMatch**](/en/reference/errors/astro-glob-no-match/)\
  Astro.glob() did not match any files.
* [**RedirectWithNoLocation**](/en/reference/errors/redirect-with-no-location/)\
  A redirect must be given a location with the `Location` header.
* [**UnsupportedExternalRedirect**](/en/reference/errors/unsupported-external-redirect/)\
  Unsupported or malformed URL.
* [**InvalidDynamicRoute**](/en/reference/errors/invalid-dynamic-route/)\
  Invalid dynamic route.
* [**MissingSharp**](/en/reference/errors/missing-sharp/)\
  Could not find Sharp.
* [**UnknownViteError**](/en/reference/errors/unknown-vite-error/)\
  Unknown Vite Error.
* [**FailedToLoadModuleSSR**](/en/reference/errors/failed-to-load-module-ssr/)\
  Could not import file.
* [**InvalidGlob**](/en/reference/errors/invalid-glob/)\
  Invalid glob pattern.
* [**FailedToFindPageMapSSR**](/en/reference/errors/failed-to-find-page-map-ssr/)\
  Astro couldn’t find the correct page to render
* [**MissingLocale**](/en/reference/errors/missing-locale/)\
  The provided locale does not exist.
* [**MissingIndexForInternationalization**](/en/reference/errors/missing-index-for-internationalization/)\
  Index page not found.
* [**IncorrectStrategyForI18n**](/en/reference/errors/incorrect-strategy-for-i18n/)\
  You can’t use the current function with the current strategy
* [**NoPrerenderedRoutesWithDomains**](/en/reference/errors/no-prerendered-routes-with-domains/)\
  Prerendered routes aren’t supported when internationalization domains are enabled.
* [**MissingMiddlewareForInternationalization**](/en/reference/errors/missing-middleware-for-internationalization/)\
  Enabled manual internationalization routing without having a middleware.
* [**CantRenderPage**](/en/reference/errors/cant-render-page/)\
  Astro can’t render the route.
* [**UnhandledRejection**](/en/reference/errors/unhandled-rejection/)\
  Unhandled rejection
* [**i18nNotEnabled**](/en/reference/errors/i18n-not-enabled/)\
  i18n Not Enabled
* [**i18nNoLocaleFoundInPath**](/en/reference/errors/i18n-no-locale-found-in-path/)\
  The path doesn’t contain any locale
* [**RouteNotFound**](/en/reference/errors/route-not-found/)\
  Route not found.
* [**EnvInvalidVariables**](/en/reference/errors/env-invalid-variables/)\
  Invalid Environment Variables
* [**ServerOnlyModule**](/en/reference/errors/server-only-module/)\
  Module is only available server-side
* [**RewriteWithBodyUsed**](/en/reference/errors/rewrite-with-body-used/)\
  Cannot use Astro.rewrite after the request body has been read
* [**ForbiddenRewrite**](/en/reference/errors/forbidden-rewrite/)\
  Forbidden rewrite to a static route.
* [**UnknownFilesystemError**](/en/reference/errors/unknown-filesystem-error/)\
  An unknown error occurred while reading or writing files to disk.
* [**CannotExtractFontType**](/en/reference/errors/cannot-extract-font-type/)\
  Cannot extract the font type from the given URL.
* [**CannotDetermineWeightAndStyleFromFontFile**](/en/reference/errors/cannot-determine-weight-and-style-from-font-file/)\
  Cannot determine weight and style from font file.
* [**CannotFetchFontFile**](/en/reference/errors/cannot-fetch-font-file/)\
  Cannot fetch the given font file.
* [**CannotLoadFontProvider**](/en/reference/errors/cannot-load-font-provider/)\
  Cannot load font provider
* [**ExperimentalFontsNotEnabled**](/en/reference/errors/experimental-fonts-not-enabled/)\
  Experimental fonts are not enabled
* [**FontFamilyNotFound**](/en/reference/errors/font-family-not-found/)\
  Font family not found
* [**CspNotEnabled**](/en/reference/errors/csp-not-enabled/)\
  CSP feature isn’t enabled

## CSS Errors

[Section titled “CSS Errors”](#css-errors)

* [**UnknownCSSError**](/en/reference/errors/unknown-csserror/)\
  Unknown CSS Error.
* [**CSSSyntaxError**](/en/reference/errors/csssyntax-error/)\
  CSS Syntax Error.

## Markdown Errors

[Section titled “Markdown Errors”](#markdown-errors)

* [**UnknownMarkdownError**](/en/reference/errors/unknown-markdown-error/)\
  Unknown Markdown Error.
* [**MarkdownFrontmatterParseError**](/en/reference/errors/markdown-frontmatter-parse-error/)\
  Failed to parse Markdown frontmatter.
* [**InvalidFrontmatterInjectionError**](/en/reference/errors/invalid-frontmatter-injection-error/)\
  Invalid frontmatter injection.
* [**MdxIntegrationMissingError**](/en/reference/errors/mdx-integration-missing-error/)\
  MDX integration missing.
* [**UnknownConfigError**](/en/reference/errors/unknown-config-error/)\
  Unknown configuration error.
* [**ConfigNotFound**](/en/reference/errors/config-not-found/)\
  Specified configuration file not found.
* [**ConfigLegacyKey**](/en/reference/errors/config-legacy-key/)\
  Legacy configuration detected.

## CLI Errors

[Section titled “CLI Errors”](#cli-errors)

* [**UnknownCLIError**](/en/reference/errors/unknown-clierror/)\
  Unknown CLI Error.
* [**GenerateContentTypesError**](/en/reference/errors/generate-content-types-error/)\
  Failed to generate content types.

## Content Collection Errors

[Section titled “Content Collection Errors”](#content-collection-errors)

* [**UnknownContentCollectionError**](/en/reference/errors/unknown-content-collection-error/)\
  Unknown Content Collection Error.
* [**RenderUndefinedEntryError**](/en/reference/errors/render-undefined-entry-error/)\
  Attempted to render an undefined content collection entry.
* [**GetEntryDeprecationError**](/en/reference/errors/get-entry-deprecation-error/)\
  Invalid use of `getDataEntryById` or `getEntryBySlug` function.
* [**InvalidContentEntryFrontmatterError**](/en/reference/errors/invalid-content-entry-frontmatter-error/)\
  Content entry frontmatter does not match schema.
* [**InvalidContentEntryDataError**](/en/reference/errors/invalid-content-entry-data-error/)\
  Content entry data does not match schema.
* [**ContentLoaderReturnsInvalidId**](/en/reference/errors/content-loader-returns-invalid-id/)\
  Content loader returned an entry with an invalid `id`.
* [**ContentEntryDataError**](/en/reference/errors/content-entry-data-error/)\
  Content entry data does not match schema.
* [**LiveContentConfigError**](/en/reference/errors/live-content-config-error/)\
  Error in live content config.
* [**ContentLoaderInvalidDataError**](/en/reference/errors/content-loader-invalid-data-error/)\
  Content entry is missing an ID
* [**InvalidContentEntrySlugError**](/en/reference/errors/invalid-content-entry-slug-error/)\
  Invalid content entry slug.
* [**ContentSchemaContainsSlugError**](/en/reference/errors/content-schema-contains-slug-error/)\
  Content Schema should not contain `slug`.
* [**MixedContentDataCollectionError**](/en/reference/errors/mixed-content-data-collection-error/)\
  Content and data cannot be in same collection.
* [**ContentCollectionTypeMismatchError**](/en/reference/errors/content-collection-type-mismatch-error/)\
  Collection contains entries of a different type.
* [**DataCollectionEntryParseError**](/en/reference/errors/data-collection-entry-parse-error/)\
  Data collection entry failed to parse.
* [**DuplicateContentEntrySlugError**](/en/reference/errors/duplicate-content-entry-slug-error/)\
  Duplicate content entry slug.
* [**UnsupportedConfigTransformError**](/en/reference/errors/unsupported-config-transform-error/)\
  Unsupported transform in content config.
* [**FileParserNotFound**](/en/reference/errors/file-parser-not-found/)\
  File parser not found
* [**FileGlobNotSupported**](/en/reference/errors/file-glob-not-supported/)\
  Glob patterns are not supported in the file loader

## Action Errors

[Section titled “Action Errors”](#action-errors)

* [**ActionsWithoutServerOutputError**](/en/reference/errors/actions-without-server-output-error/)\
  Actions must be used with server output.
* [**ActionsReturnedInvalidDataError**](/en/reference/errors/actions-returned-invalid-data-error/)\
  Action handler returned invalid data.
* [**ActionNotFoundError**](/en/reference/errors/action-not-found-error/)\
  Action not found.
* [**ActionCalledFromServerError**](/en/reference/errors/action-called-from-server-error/)\
  Action unexpected called from the server.
* [**ActionsCantBeLoaded**](/en/reference/errors/actions-cant-be-loaded/)\
  Can’t load the Astro actions.

## Session Errors

[Section titled “Session Errors”](#session-errors)

* [**SessionStorageInitError**](/en/reference/errors/session-storage-init-error/)\
  Session storage could not be initialized.
* [**SessionStorageSaveError**](/en/reference/errors/session-storage-save-error/)\
  Session data could not be saved.
* [**SessionWithoutSupportedAdapterOutputError**](/en/reference/errors/session-without-supported-adapter-output-error/)\
  Sessions cannot be used with an adapter that doesn’t support server output.
* [**SessionConfigMissingError**](/en/reference/errors/session-config-missing-error/)\
  Session storage was enabled but not configured.
* [**SessionConfigWithoutFlagError**](/en/reference/errors/session-config-without-flag-error/)\
  Session flag not set
* [**CannotOptimizeSvg**](/en/reference/errors/cannot-optimize-svg/)\
  Cannot optimize SVG