Unable to install Boot Camp 6 Update for Windows 10 due an invalid signature

I previously upgraded to Windows 10 on my MacBook Pro (Mid 2012)'s Windows (former W7) Partition. Sadly I'm unable to install the BootCamp 6 update - it fails during the installation. Following error message pops up:

Error Message 1: "Errors occured while installing the updates. If the problem persists, choose Tools - Download Only and try installing manually"

If I do so, following message shows up:

Error Message 2: "Boot Camp 6 Update for Windwos 10 has an invalid signature. The download has been removed."

I couldn't find any Boot Camp 6 installer online... Neither a possibility to update Boot Camp on my OSX El Capitan Partition?

Any solution to fix this problem?


Found that enabling developer mode under "Update & Security" in the system settings allowed the Boot Camp 6 update to install with no issue.