hugo/docs/content/en/functions/errorf.md

title	description	date	publishdate	lastmod	categories	menu	keywords	signature	workson	hugoversion	relatedfuncs	deprecated
errorf and warnf	Log ERROR or WARNING from the templates.	2017-09-30	2017-09-30	2017-09-30	functions	docs parent functions	strings log error	errorf FORMAT INPUT			printf	false

errorf or warnf will evaluate a format string, then output the result to the ERROR or WARNING log (and only once per error message to avoid flooding the log).

Any ERROR will also cause the build to fail (the hugo command will exit -1).

Both functions return an empty string, so the messages are only printed to the console.

{{ errorf "Failed to handle page %q" .Path }}

{{ warnf "You should update the shortcodes in %q" .Path }}

Note that errorf and warnf support all the formatting verbs of the fmt package.