I know I am not the only person to have problems with the usbc – HDMI screen suddenly stop working and I thought I would never fix it today, but I have finally done it so thought I would share the technique – because it calls on a number of posts to resolve it.
Uninstall DisplayLink
First thing you need to do is uninstall the DisplayLink software extension that enables the USBC – HDMI link
- open spotlight and search for DisplayLink Uninstaller
- double click on the installer and follow the instructions to uninstall the driver
- when you are prompted to restart your computer then do so
Reboot in Recovery Mode
- as your system is coming back up hit <CMD> <R>
When the system comes up in recovery mode do the following
- login as yourself
Mount your Hard Drive
- open diskutility
- mount your hard drive
- close diskutility
Invalidate the Kernel Extension Cache
- from the top menu select Utilities -> terminal
- type in the following command
kextcache -i /Volumes/<your harddrive>to find out your hard drive type
ls /Volumesthis will list your hard drive.
If the name of your hard drive contains spaces start typing the name of your hard drive before the spaces and then press tab
For example – if your hardrive is called Macintosh HD then type
kextcache -i /Volumes/Macand then press tab. The command line will complete the name for you (in this case it will display
kextcache -i /Volumes/Macintosh\ HDOnce the command has completed it will display a number on the command line.
Reboot as Normal
Type
rebootand let your computer come back up as normal
Install DisplayLink
- Download the Catalina Display Link driver from https://www.displaylink.com/downloads/macos
- double click the downloaded software and click install
- when prompted restart your computer
Final Troubleshooting
When your computer restarts your second screen may still not appear. There are three checks to carry out:
1: Security and Privacy – DisplayLink Permissions
- click on the Apple icon
- open System Preferences -> Security and Privacy
- click on the general tab
check that the DisplayLink app has not been prevented from running and if so click on the allow apps from DriverLink if it appears (not shown above)
2: DisplayLink Permissions to Record the Screen
check to see if the DisplayLink app has appeared in the Screen Recording window of the Privacy tab. If it is there then allow it to do screen recording
3: Manually start the DisplayLink app
Open a terminal window and type the following:
cd /Library/PrivilegedHelperTools/DisplayLink/DisplayLinkUserAgent.app/Contents/MacOS
./DisplayLinkUserAgentwait for a few minutes and your screen should come to life.
When it does, <ctrl> c in the command line and restart your computer
References
- https://www.displaylink.com/downloads/macos
- https://support.apple.com/en-us/HT201314
- https://www.displaylink.org/forum/showthread.php?s=d774a5eaa3b5d9627e95616d634a8238&t=66641
- https://plugable.com/drivers/displaylink/mac/
- https://support.displaylink.com/knowledgebase/articles/533875-how-to-identify-the-displaylink-software-version-i
Skills421 