How To Fix No HDMI Signal After macOS Catalina Update

 
 

Fix No HDMI Signal After macOS Catalina Update

Overview: There are multiple users who are facing No HDMI Signal after upgrading Mac to macOS Catalina. In this post we will try various troubleshooting steps to fix the external display issue on macOS Catalina. Let start with real life scenarios.

No HDMI Signal After macOS Catalina Update

After updating to Catalina, Mac Mini 2018 does not send any HDMI signal. It was working fine today, until the Catalina update. Cannot enter safe mode nor recovery mode. Tried resetting NVRAM, no change. Just in case, I tried another cable and I also tried connecting it to AVR, but still no signal. Mini is connected to 4K TV, I don’t have any other option (except USB-C to HDMI adapter which I don’t have).

Source: Apple Community

Just like the above user there are many others who are facing external display issue after upgrading the macOS to Catalina.

Plug out and Plugin

Before troubleshooting make sure there is no damage to the HDMI cable or HDMI ports.

  • Press and hold the power button to shut down your Mac.
  • Disconnect the power cable or charger from your Mac.
  • Disconnect or unplug the HDMI cable from your Mac and wait for 25-30 seconds.
  • Now plug in the power and HDMI cable to your Mac, wait for few seconds and start your Mac.

Note: If your external display has 30Hz non HDR HDMI ports then try connecting Mac to those ports. Also, if you have a 4K /60HZ monitor or TV, buy USB-C to HDMI adapter.

Fix Thunderbolt to HDMI Issue macOS Catalina

  • Power off your TV/external display and unplug the thunderbolt cable from your Mac.
  • Go to System Preferences>Security & Privacy.
  • Disable the firewall which you can find under the firewall option, click on lock icon in case required to make changes.
  • With your TV off, plug in the thunderbolt cable to your Mac and the other end to the TV HDMI port.
  • Now power on your TV, select the input source as HDMI and that should take care of the display of your mac on your TV.
  • Navigate to the System Preferences>Displays and here you can see that Mac identifies your external display. You can change resolutions and other settings here.

Resetting the TV or External Display

Many users were able to resolve the issue after resetting the external display to its factory settings. Try this to fix no video issue.

Update Display Driver or Additional Software Required

Check if video adapter or monitor requires driver update. Expensive monitors sometimes requires additional software to get it working. Please make sure that you install any software which is required to support external display.

Few users were able to resolve the issue after updating the Display Link Driver.

Fix Black Screen Issue on External Display macOS Catalina.

  • Go to System Preferences and click on Security & Privacy.
  • Select Screen Recording located on the left side and enable the Display Driver.
  • You can also make changes with the resolution and check which one does the trick.

Start Mac in Safe Mode and Check the Display

  • Shut down your Mac.
  • Now start your Mac and immediately Press and hold the Shift key as soon as the start-up sound is heard.
  • Release the Shift key when you see the Apple logo. Safe Boot appears on the macOS Catalina start-up screen.

Safe Mode restricts the use of many applications on the system and allows examination in a more restricted environment. In case the external display works fine in Safe Mode then you have to isolate the software which is causing the issue.

Reset SMC

  • Go to the Apple menu and shut down your Mac.
  • Once Mac shuts down, press and hold the Shift-Control-Option on the left side of the built-in keyboard, then press the power button at the same time. Hold these keys and the power button for 10-15 seconds.
  • Now Release all keys.
  • Press the power button again to turn on your Mac.

For iMac computers

  • Go to the Apple menu and shut down your Mac.
  • Unplug the power cable.
  • Wait 15-20 seconds.
  • Plug in the power cable back.
  • Wait for 10 seconds and start your Mac.

Reset PRAM and NVRAM

  • Shut down Mac
  • After few seconds start the Mac and press and hold Option, Command, P and R keys on the keyboard together.
  • Hold the keys down till the Mac reboots and you hear a beeping sound.



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