In sequenceserver 3.1.2 the blast binaries are not found Error is
Errno::ENOENT - No such file or directory - blastn:

In the sequenceserver.conf the :bin: is pointing to the correct directory.
Sequenceserver is working if I change task.rb to

      help_text = `/usr/prg/ncbi-blast-2.16.0+/bin/#{algorithm} -help`

(Sorry, I do not do Ruby normally)