Reported on IRC, MW 1.31.2, MySQL 5.7.26-0ubuntu0.18.04.1
Search string was Blueberry - De samlede eventyr
Seems the issue has been around a long time - https://www.mediawiki.org/wiki/Topic:Rz5tsfylmgjdmlvp (since at least 1.21)
[XP@91yP-rZLZDBuH3rzr-wAAAAI] /index.php?title=Speciel%3AS%C3%B8gning&search=Blueberry%20-%20De%20samlede%20eventyr&fulltext=1 Wikimedia\Rdbms\DBQueryError from line 1457 of /var/www/html/includes/libs/rdbms/database/Database.php: A database query error has occurred. Did you forget to run your application's database schema updater after upgrading?
Query: SELECT page_id,page_namespace,page_title FROM `mw_page`,`mw_searchindex` WHERE (page_id=si_page) AND ( MATCH(si_title) AGAINST('+blueberry +- +deu800 +samlede +eventyr ' IN BOOLEAN MODE) ) AND page_namespace = '0' LIMIT 20
Function: SearchMySQL::searchInternal
Error: 1064 syntax error, unexpected '-' (localhost)
Backtrace:
#0 /var/www/html/includes/libs/rdbms/database/Database.php(1427): Wikimedia\Rdbms\Database->makeQueryException(string, integer, string, string)
#1 /var/www/html/includes/libs/rdbms/database/Database.php(1200): Wikimedia\Rdbms\Database->reportQueryError(string, integer, string, string, boolean)
#2 /var/www/html/includes/libs/rdbms/database/Database.php(1653): Wikimedia\Rdbms\Database->query(string, string)
#3 /var/www/html/includes/search/SearchMySQL.php(191): Wikimedia\Rdbms\Database->select(array, array, array, string, array, array)
#4 /var/www/html/includes/search/SearchMySQL.php(178): SearchMySQL->searchInternal(string, boolean)
#5 /var/www/html/includes/specials/SpecialSearch.php(318): SearchMySQL->searchTitle(string)
#6 /var/www/html/includes/specials/SpecialSearch.php(185): SpecialSearch->showResults(string)
#7 /var/www/html/includes/specialpage/SpecialPage.php(565): SpecialSearch->execute(NULL)
#8 /var/www/html/includes/specialpage/SpecialPageFactory.php(568): SpecialPage->run(NULL)
#9 /var/www/html/includes/MediaWiki.php(288): SpecialPageFactory::executePath(Title, RequestContext)
#10 /var/www/html/includes/MediaWiki.php(861): MediaWiki->performRequest()
#11 /var/www/html/includes/MediaWiki.php(524): MediaWiki->main()
#12 /var/www/html/index.php(42): MediaWiki->run()
#13 {main}