TROUBLESHOOTING: Video card not seen in High Sierra

Some users have complained that their video device was not seen after an upgrade to High Sierra. In their case, it was related to a new protection mechanism in High Sierra that requires user approval before loading new third-party kernel extensions.

The problem is that video devices use Kernel Extensions, and if their "kext" is not loaded then the card won't be seen by the system.

If the drivers were installed before an upgrade to High Sierra then there won't be any issue. But if they are installed afterwards, the user will need to approve them. The approval is done in "System Preferences > Security & Privacy". See the following screenshots to approve Blackmagic-Design's kext:


The problem is that this message is displayed only 30 minutes after it was displayed. So the user will have to reboot the computer to see it again.

Also, with Blackmagic-Design the message may only displayed if a video device is connected.

If needed it is possible to check in Terminal with a command line for example with AJA's kext):

~ admin$ sudo kextutil /Library/Extensions/AJANTV2.kext

For Blackmagic-Design it will be:

~ admin$ sudo kextutil /Library/Extensions/DeckLink_Driver.kext

It will ask for the admin password and if the extension can not be loaded it will return something like this:

Kext rejected due to system policy: <OSKext 0x7fb95472b540 [0x7fff97b7e5b0]> { URL = "file:///Library/StagedExtensions/Library/Extensions/AJANTV2.kext/", ID = "com.aja.iokit.ntv2" }
Kext rejected due to system policy: <OSKext 0x7fb95472b540 [0x7fff97b7e5b0]> { URL = "file:///Library/StagedExtensions/Library/Extensions/AJANTV2.kext/", ID = "com.aja.iokit.ntv2" }
Diagnostics for /Library/Extensions/AJANTV2.kext:

More info on this can be found here:

Have more questions? Submit a request


Powered by Zendesk