Comment 2 for bug 578400

It's looking for the uncompressed /usr/share/doc/qcad/html/qcaddoc.adp.gz at the absolute path /qcaddoc.adp
If you symlink it from the root directory it will open the manual, but then expect the rest of the html documentation to be available relative to /.

Upstream bug ? It would seem that a documentation path should be prepended to the /qcaddoc.adp string, whether at build time, in configuration or from an environment variable, and the cad-doc installation should uncompress the qcaddoc.adp file.