Tunnelblick Help
System Requirements Not Met: A system folder is not secure
NOTE: Online documentation may be more up-to-date. See System Folder Security.
Tunnelblick will not run if the folders that it uses on the boot volume are not secure. Tunnelblick secures the folders that it creates, but it does not modify system folders. The macOS installation process sets up system folders to be secure, so for most users this does not cause any problems.
However, several third-party installation programs modify the standard ownership or permissions of some system folders incorrectly. The systems on which these installers have been run have less secure ownership or permissions settings on these important system folders.
Repairing with Disk Utility
If you are using macOS 10.10 ("Yosemite") or earlier, try to fix the problem by using the macOS Disk Utility program:
macOS 10.11 ("El Capitan") does not have a "Repair Disk Permissions" button, so you will need to repair the permissions manually. You will also need to repair the ownership and permissions manually if Disk Utility does not fix the problem. For instructions see System Folder Security.