hugo/docs/content/en/_common/ref-and-relref-error-handling.md

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Do not remove front matter.

By default, Hugo will throw an error and fail the build if it cannot resolve the path. You can change this to a warning in your site configuration, and specify a URL to return when the path cannot be resolved.

{{< code-toggle file=hugo >}} refLinksErrorLevel = 'warning' refLinksNotFoundURL = '/some/other/url' {{< /code-toggle >}}