• In open Ubuntu 18.04 machine click Parallels Actions -> "Install Parallels Tools"

• A "Parallels Tools" CD will popup on your Ubuntu desktop.

• Open it by double mouse click, copy all the content to a new, empty directory on a desktop, let's name it "parallels_fixed"

• Open terminal, change directory to parallels_fixed (cd ~/Desktop/parallels_fixed)

• Make command line installer executable (chmod +x install)

• Change directory to "installer" now (cd installer)

• Run this command to make few scripts executable: "chmod +x installer.* .sh prl_"

• Go to kmods directory (cd ~/Desktop/parallels_fixed/kmods) and extract the files (tar -xzf prl_mod.tar.gz)
• Remove prl_mod.tar.gz file from that directory.

• Go to "prl_eth/pvmnet/" (cd ~/Desktop/parallels_fixed/kmods/prl_eth/pvmnet) directory
• Open "pvmnet.c" file in a text editor
• Edit line 438:

  MODULE_LICENSE("Parallels");

to MODULE_LICENSE("GPL");

• Save

• Go to "prl_tg/Toolgate/Guest/Linux/prl_tg/" (cd ~/Desktop/parallels_fixed/kmods/prl_tg/Toolgate/Guest/Linux/prl_tg) directory
• Open "prltg.c" file in a text editor
• Edit line 1535: MODULE_LICENSE("Parallels"); to MODULE_LICENSE("GPL");
• Save

• Go to "prl_fs_freeze/Snapshot/Guest/Linux/prl_freeze/" (cd ~/Desktop/parallels_fixed/kmods/prl_fs_freeze/Snapshot/Guest/Linux/prl_freeze)

• Open "prl_fs_freeze.c" file in a text editor

• in line 212 you will find a function "thaw_timer_fn": ` void thaw_timer_fn(unsigned long data) { struct work_struct *work = (struct work_struct *)data;

  schedule_work(work); } `