No HDMI signal after update

No! Even the new adapter, model A2119, does NOT guarantee 3840x2160 at 60Hz - https://support.apple.com/en-ca/HT207806

As a matter of fact the Mac Mini isn't even mentioned in the material from Apple:

Model A2119 is the newest model of this adapter. It supports HDMI 2.0 at these resolutions and refresh rates when used with macOS Mojave 10.14.6 or later or iOS 12.4 or later. It also supports HDR video in HDR10 and Dolby Vision formats when connected to a compatible playback device and display, TV, or projector.

• Up to 1080p at 60Hz
• 3840 x 2160 at 30Hz
• 3840 x 2160 at 60Hz with these devices:
  • 15-inch MacBook Pro introduced in 2017 or later
  • Retina iMac introduced in 2017 or later
  • iMac Pro
  • iPad Pro

Recently updated to macOS 10.15.1, display issue via hdmi persists

• Running a primary display (Scepter 27" 4k monitor via usb-c to DisplayPort) (functioning with image)
• Running a secondary display (Hisense 50" 4k TV via hdmi to hdmi @ 60hz (not functioning - no image)
• Force restarted the Mac mini
• Disconnected/Reconnected multiple cables and different displays
• Reset SMC
• Followed all troubleshooting from https://support.apple.com/en-us/HT201177

Anyone else still having issues after updating to macOS 10.15.1?

It may be that the LG's "Color" feature is directly related to HDR ... and this may be the common clue here with the mini's HDMI port. My Dell does allow me to switch HDR on or off, so I had to resort to using a USB-C-to-HDMI adapter to get my mini to display.

Interestingly the Apple Technical Specs for the 2018 mini do not include any information about HDR support, but does inform us that this mini does have a HDMI 2.0 port ... which according to the standards, supports HDR.

FWIW. I think we all share the same frustration with using the HDMI port on the 2018 Mac mini with 4K monitors. However, whether it's macOS, Windows, Linux, you name it, any first major release to the public is still a "beta" ... and it's the conundrum of having the very latest vs. bug free. It would be impractical, if not impossible, to test every possible combination of hardware to verify perfect operation, that's why we see X.1, X.2, X.3, etc. releases not long after. Can Apple do better ... sure! But, two ways to assist Apple, is to participate in the public or developer betas and providing Apple with direct feedback when something isn't working. This forum is intended to be a means for Apple-product users to support each other with potential solutions. In this case, this issue appears to be around using the HDMI interface on the mini with 4K monitors, especially with HDR support ... and so far, either disabling HDR and continue to use the HDMI or switch to using the USB-C-to-HDMI adapter are the only potential workarounds. Maybe with Catalina 15.1, Apple will hear us and offer a fix.

One suggestion to everyone here, is if you want to try any new OS release, major or minor, create a bootable clone of your Mac's drive to an external one. Upgrade that cloned drive to that new release and try it out for a few days or weeks making sure that all of your critical apps and hardware work as you expect it to ... and, if you are satisfied that it does, then upgrade your system drive. This way you have the opportunity to "test drive" it before "buying" it.

Just have the bulletin from someone else, text below.

Apple Technical Service Bulletin

This document provides additional instructions for operating the Mac Mini (Late 2018)

macOS Catalina 10.15

Mac Mini (Late 2018) users should refrain from upgrading to macOS Catalina 10.15.

https://www.apple.com/macos/catalina/

Information about products not manufactured by Apple, or independent websites not

controlled or tested by Apple, is provided without recommendation or endorsement. Apple

assumes no responsibility with regard to the selection, performance, or use of third-party

websites or products. Apple makes no representations regarding third-party website

accuracy or reliability. Risks are inherent in the use of the Internet. Contact the vendor for

additional information. Other company and product names may be trademarks of their

respective owners.

Published Date: October 12, 2019

Only 30 Hz possible (https://support.apple.com/en-us/HT207806)

Intel UHD Graphics 630:

  Chipset Model: Intel UHD Graphics 630

  Type: GPU

  Bus: Built-In

  VRAM (Dynamic, Max): 1536 MB

  Vendor: Intel

  Device ID: 0x3e9b

  Revision ID: 0x0000

  Metal: Supported, feature set macOS GPUFamily2 v1

  Displays:

LG Ultra HD:

  Resolution: 3840x2160 (2160p/4K UHD 1 - Ultra High Definition)

  UI Looks like: 1920 x 1080 @ 30 Hz

  Framebuffer Depth: 30-Bit Colour (ARGB2101010)

  Main Display: Yes

  Mirror: Off

  Online: Yes

  Rotation: Supported

  Adapter Type: Apple USB-C Digital AV Adapter

  Automatically Adjust Brightness: No

  Adapter Firmware Version: 2,35

Don't know if it has been mentioned here before but there is a special page to report any bug here : https://www.apple.com/feedback

I contacted the support again and they told me that the apple dev team is looking at those feedbacks.

I guess it is more effective to contact them directly rather than discussing between us.

I hope this issue will be fix quickly, it's very crippling.

Using an alternative cable USB-C (Mac Mini 2018) --> Display Port (Samsung U28E850 4k), works with 10.15

1. SMC Reset
2. NVRAM Reset
3. Update to 10.15.1
4. Boot first time after finishing update with alternative cable USB-C --> Display Port
5. Shoot down
6. Change cable HDMI (Mac) --> HDMI1 30Hz (Samsung U28E850 4k): works also by starting, login and after login
7. Shoot down
8. Change same cable to HDMI2 60Hz, works also by starting, login and after login

Good luck.

I fixed my full time pink screen issue, here is the solution. I think it might apply to your issue as well. For those of you without working screens, I suggest finding a screen that does work temporarily, and installing Teamviewer, or some other free program to remotely log into your machine. After doing so, connect the nonworking screen, start the computer, and log in remotely, then follow the steps 1-5 below. you will have to switch back to the working screen for the steps 6-15

The reason it is having an issue, is after the update, the signal being sent is YCbCr instead of RGB like your monitors are expecting. Some people with panels like mine will get pink, others likely get no signal recognized. This script works by setting up a profile for your specific monitor, and having it be forced to be RGB, if you connect it to another model monitor with the same issue, this process will need to be repeated for that monitor as well.

1. Download this script: https://gist.github.com/adaugherity/7435890
2. Place the patch-edid.rb file into the /Users/ directory
3. Run this command in Terminal: ruby /Users/patch-edid.rb
4. Take note of the DisplayProductID and DisplayVendorID file names. These will vary based on your monitor.
5. Move the output file named "DisplayProductID-XXXX" from /Users/~username/ to the /Users/ directory
6. Reboot your Mac in Recovery Mode by pressing Command+R as soon as you see the Apple logo after rebooting
7. Open Disk Utility in Recover Mode
8. Check to see if "Macintosh HD" is mounted. If it isn't you will need to mount it before proceeding.
9. Exit Disk Utility
10. Open Terminal in Recovery Mode
11. Change to the Overrides directory via "cd /Volumes/Macintosh\ HD/System/Library/Displays/Contents/Resources/Overrides/"
12. Create the folder with "mkdir DisplayVendorID-XXXX".
13. Run this command in Terminal (make sure to include spaces):
14. "cp /Volumes/Macintosh\ HD/Users/DisplayProductID-XXXX /Volumes/Macintosh\ HD/System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-XXXX/"
15. Restart computer and the monitor should now be in RGB mode.
16. Check to make sure it has taken effect by going to your "system preferences" and clicking "displays". If your display name at the top bar does not include "forced RGB mode (EDID override)", it did not take effect.

Hope this helps everyone! if you have issues look in the comments on the script page, the author is active.

My machine is a Mac mini (2018) i7 64GB 1TB. My monitor is a 28 inch Hannspree HF289H monitor

Same problem here with my Mac mini 2018.

Just upgraded to Catalina, now same problems with HDMI connection to my 4k Samsung display.

Lower resolution displays work fine even connecting via HDMI.

No problems with Mojave before.

Maybe this will help you to activate HDMI:

Changed monitor setting to "standard for monitor",

Shutdown MacMini,

Disconnect all monitor cables except HDMI,

Start the MacMini.

If it is set on Scaled the HDMI will not work.

Good luck!

Same issue — Dell P2415Q 4K monitor connected to Mac Mini 2018 via HDMI @ 60 Hz. Worked well on Mojave. With Catalina, -sometimes the monitor is detected and the Mac tries to use it, but never gets a picture — only a black screen. Sometimes it is not detected at all. Two other monitors (same model) connected via USB C to DisplayPort are still working fine, so the problem seems specific to HDMI.

I’ve tried switching to a better, 8K HDR compatible, HDMI cable but that made no difference. Resetting NVRAM didn’t help either.

C’mon, Apple. I could have this kind of fun with Windows. I was hoping to get away from it.