Symptoms:

Lucid fails to mount your file space and in the meanwhile you see a dialog window saying that the FUSE extension developed by Benjamin Fleischer needs to be allowed explicitly.


Solution:

Click on “Open System Preferences” button in the dialog, or if you closed it go to  "System Preferences > Security & Privacy > General".
Then click the Allow button to enable the FUSE extension


Possible problems:

  • No Allow button in System Preferences. If you opened the System Preferences more than 30 minutes after you saw the “System Extension Blocked” dialog the Allow button will have disappeared from system preferences. Try to mount a Lucid filespace again and then go to System Preferences straightaway.

  • Clicking the Allow button does not work. For security reasons only trusted Apple hardware devices can be used to click on the allow button. If you are using an external mouse from another vendor it might not work. Additionally, apps that offer extended user experience might be capturing the user input and transferring it to the system. This turns hardware clicks into software clicks and macOS does not accept those on the Allow button.


Reason:

Latest updates in macOS High Sierra require explicit approvement for loading of third party kernel extension modules.
Lucid leverages the FUSE (osxfuxe) kernel extension, developed by Benjamin Fleischer. Therefore, in order to mount a Lucid filespace users need to approve this extension.


External resources:

Apple Technical Note: https://developer.apple.com/library/archive/technotes/tn2459/_index.html#//apple_ref/doc/uid/DTS40017658
Apple Developer Forums Thread: https://forums.developer.apple.com/thread/79172
Related OSX Fuse Issue: https://github.com/osxfuse/osxfuse/issues/437