I'm reluctant to erase and re-install Sierra on my existing boot drive, so I'm thinking of removing my 750 Gb boot drive and installing a 500 Gb SSD boot drive and re-installing Sierra on it, then erasing and re-installing my removed 750 Gb drive with OWC's Data Doubler, then using Migration to restore my data. I have Carbon Copy Cloned it, so I have the data backed up. I have received cryptic messages - gray screen with earth in the center with an exclamation point in a triangle superimposed, with '/support' and '-4400D' or '-5010D' below the earth. I've attempted to re-install Sierra on my existing boot volume several times, and it's always failed with 24 seconds remaining, with the message: 'An error occurred while preparing the installation. I've run the extended hardware test, and no trouble was found. It supports torrent files magnet links, has its own built-in search, and offers download prioritization. It’s easy to use, free, and open-source, yet it’s packed with features. My 2011 15' MacBook Pro with OS 10.12.5 will not boot without errors, and usually only in Safe Mode. Conclusion: qBittorrent’s familiar interface makes it one of the best torrent clients available for Mac.

Refit did not work on mac os 10.12