As search.musicbrainz.org has been closed last week, there is no alternative to installing a local search server for a MusicBrainz mirror to handle search requests. This isn't strictly needed for mirrors that are mainly set up for lookup/browse requests. In this setup the server fails miserably on casual search requests made through either the website or the webservice.

Ideally mirrors should redirect to musicbrainz.org for search endpoints. This search-disabled mode could be set on when SEARCH_SERVER is not set (at all) and WEB_SERVER is not to musicbrainz.org.