gohugoio/hugo · warning

multihost change detected, please restart server

Error message

multihost change detected, please restart server

What it means

Returned by reloadConfig during a live config reload in `hugo server` when the number of configured languages changed and either the old or new configuration is multihost (per-language baseURLs). The multihost server wires one HTTP server per language at startup, so adding/removing a language can't be applied via hot reload and Hugo asks for a restart instead of serving an inconsistent state.

Source

Thrown at commands/hugobuilder.go:1181

	return
}

func (c *hugoBuilder) reloadConfig() error {
	c.r.resetLogs()
	c.r.configVersionID.Add(1)

	if err := c.withConfOrOldConfE(func(conf *commonConfig) error {
		oldConf := conf
		c.conf = nil
		newConf, err := c.r.ConfigFromConfig(configKey{counter: c.r.configVersionID.Load()}, conf)
		if err != nil {
			return err
		}
		sameLen := len(oldConf.configs.Languages) == len(newConf.configs.Languages)
		if !sameLen {
			if oldConf.configs.IsMultihost || newConf.configs.IsMultihost {
				return errors.New("multihost change detected, please restart server")
			}
		}
		c.conf = newConf
		return nil
	}); err != nil {
		return err
	}

	if c.onConfigLoaded != nil {
		if err := c.onConfigLoaded(true); err != nil {
			return err
		}
	}

	return nil
}

View on GitHub ↗ (pinned to 8a468df065)

Solutions

1. Stop and restart `hugo server` — the new language set will be picked up on startup.
2. If you want hot reloads while iterating, avoid per-language baseURLs (non-multihost) during development.

// avoid editing multihost-related config (languages' baseURL entries)
// while the dev server is running; plan such changes for a restart

if err := server.Run(); err != nil {
    if strings.Contains(err.Error(), "multihost change detected") {
        // config edit toggled multihost mode; restart the server process
        return restartServer()
    }
    return err
}

When it happens

Trigger: Editing the site config while `hugo server` is running such that len(languages) changes (adding or removing a [languages.xx] block) while multihost mode is active before or after the change — i.e. languages have distinct baseURL values.

Common situations: Iterating on a multilingual site in server mode and adding a new language section, or adding a per-language baseURL (switching into multihost) together with a language count change.

Related errors

• --appendPort=false not supported when in multihost mode
• failed to compile Headers glob %q: %w
• redirects must have either From or FromRe set
• failed to compile Redirect glob %q: %w
• failed to compile Redirect regexp %q: %w

AI-assisted analysis of gohugoio/hugo@8a468df065 (2026-07-31). Data as JSON: /data/errors/75950aaae54b46e1.json. Report an issue: GitHub ↗.