I re-installed yunohost and it worked better. It failed first because my password was too short (the screen just said “postinstall failed, retry ?”). But after yunohost tools postinstall I have unavailable dyndns subdomain, which is a known pb if you use a subdomain of nohost.me: Nohost domain recovery - Suppression de domaine en nohost.me et noho.st We then must ask the administrators to delete the subdomain.