Parallels Tools upgrade in Debian virtual machine fails with error "An error occured when downloading components for building Parallels Tools kernel modules - kernel sources. Install these components and try again":
ResolutionPlease execute the following commands in terminal window with root permissions to install packages required for kernel modules building:
apt-get install linux-headers-$(uname -r) make gcc
In the second command uname -r should be substituted with an output of the first command.
After successful installation of these packages please try to install Parallels Tools again.