System or boot drives which are encrypted by BestCrypt Volume Encryption software, require BestCrypt to be installed at all times.
To upgrade your software to a newer version, you must not uninstall the older version, which is already installed on your system.
Please make the new installation on the existing installation and restart.
The new installation will automatically takeover the previous version.
If for some reason you must uninstall the software, please decrypt your system/boot drive first.