I just fixed my update to v0.8.1 problem.  For some reason my gridseed black miner stop working after upgrading.....

1) Just SSH into your minera.
2) Delete the minera folder from /var/www
3) CD back to /var/www
4) sudo git clone https://github.com/michelem09/minera
5) sudo ./install_minera.sh ( after adding execute rights to the file)

6) lastly restall the miners software....

cd /var/www/minera
./build_miner.sh [miner-name | or empty for usage]


*** Hope this is helpful to anyone who needs it....