gohugoio/hugo · warning

multihost change detected, please restart server

Error message

multihost change detected, please restart server

What it means

During live config reload (reloadConfig), if the number of languages changes AND either the old or new config is multihost, the server cannot safely hot-swap and asks the user to restart, because multihost requires per-language port/listener reshuffling the running server cannot reconfigure.

Solutions

1. Stop and restart `hugo server` after editing languages in a multihost project
2. Avoid changing the number of languages during a live multihost session
3. Make language changes in a single edit, then restart

When it happens

Trigger: Editing config while `hugo server` runs so that the language count changes and IsMultihost is true on either side (hugobuilder.go:1178-1182).

Common situations: Adding or removing a language in a multihost setup; switching a multihost config to single-host by editing language blocks; toggling per-language baseURL.

Related errors

• --appendPort=false not supported when in multihost mode
• cache dir contains unresolved placeholders
• cannot unmarshal CSV into %T: invalid targetType: expected…
• cannot use --renderToMemory with --destination
• config needs a filename

AI-assisted analysis of gohugoio/hugo@52c9bd7908 (2026-08-09). Data as JSON: /api/errors/75950aaae54b46e1. Report an issue: GitHub.

Appendix: 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
}

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