In StructuredDiscussions version REL1_32-bf651cf some code is missing. When requesting Discussion pages or Special:SpecialPages there is the error:
Fatal error: Class 'Pimple\Container' not found in /var/www/html/wiki_1.32.0/extensions/Flow/includes/Container.php on line 5
After comparing with version REL1_31-3b30ee9 and copying (from older release) vendor/autoload.php, vendor/composer and vendor/pimple in (latest release) vendor/ the problem disappears.