And, as I found out this morning, after updating to kernel 5.3.7: DONT delete the temp directory after you're done. For some reason the build doesn't get stashed in DKMS anymore, so every time you update a kernel, you have reboot into the kernel, Ctrl-Opt-F2 into a new screen, and run the installer manually again.
So, I went back in, removed the edits on those four lines and made the change to the script instead, forcing the define to 0. That's a much cleaner way to do it, personally.
Worked for me too! I was struggling a lot with this issue.. I really have to consider if Parallels is worth buying. Works so smoothly but not being able to install the tools makes a bad impression. Thanks a lot for these detailed instructions!
Hello Everyone, Parallels released an update for Parallels Desktop 15 which resolves the issue discussed here. Download it and update Parallels Tools afterwards to resolve the issue.
Except, I'm still finding that Parallels Tools is either not rebuilding or installing correctly when a new kernel is installed. I have to do it manually after a new kernel install then rebooting. The reboot sequence never gets to the graphical login screen.