yaws packaging was not upgraded correctly
starting yaws will complain not finding setuid_drv driver.

short term fix:
cd erlang/lib/yaws-1.77/priv && ln -s linux-x86/lib
(change linux-x86 to you effective archdir of course)

long term fix:
i’ll upgrade the package this week so yaws:start() will work without change
i’ll not upgrade yaws version by now. so to apply change when new package will be ready:
cean:uninstall(yaws).
cean:install(yaws).