The latest version of the onlyoffice-documentserver package for Debian, 7.4.1, contains updates to these files:
/etc/onlyoffice/documentserver/nginx/includes/ds-docservice.conf/etc/onlyoffice/documentserver/nginx/includes/http-common.conf
That adds a $the_prefix variable, does anyone know where this is set?
I have had to delete it from ds-docservice.conf to get everything working.