Almost well known error; seen during inplace upgrades from 2010 to 2012 or 2012 to 2014.
Delete the \Puredisk\ registry key and it's child \Puredisk\Agent\. (or even rename it)
If you had done it in another inplace upgrade (from 2012 to 2014 for instance) the key will be set during this new install process again. So you have to delete or rename it once more.
After that, please restart the inplace upgrade and it should work out fine
Greets from Germany