Resolved Better Display App setting crashed and killed my 5K monitor - or my M4 Pro Mac mini's video out....

[PaulD-UK]

Hi
I was testing image quality on my M4 Pro Mac mini and I changed the Better Display Free version display mode resolution settings for my 5K DIY monitor, first to 4K, which was OK, and then to one of the 1080p settings (I don't know which one).

The monitor immediately went black, and is in effect unrecoverable, although it is still on - it has remained black, even though I can tell that MacOS is fine, but invisible.
I can enter my login password and then use Cntrl+Eject/Enter to shut the Mac mini down.

When I restart I see the progress bar and monitor splash screen briefly, then immediately the black raster appears , and that's it...

I can start in Safe mode, and I see the Options Select screen, and I see the progress bar and monitor splash screen briefly, then black...

I connected the 5K monitor to my M1 iPad Pro, and everything works fine, so no problem with the monitor itself.
I suspect that it has problems with handling a funny-mode 1080p signal.

That was yesterday evening.

Today I disconnected the 5K monitor and got an old Dell monitor that I know can handle 1080p, and connected it via HDMI.

As I expected he M4 Pro mini booted, completely as normal, and I switched off BD in it's drop down menu.

Keeping the Dell monitor running, I then tried plugging in the 5K monitor's USB-C to DP cable, in a different TB5 port.
SUCCESS! I get a normally working 5K monitor, at retina 1440p.

So I disconnected the Dell monitor, and unplugged the HDMI cable from the Mac mini.

BLACK SCREEN AGAIN....
Everything is back to as it was, broken...
So there is some BD setting that is persistently preventing the 5K monitor getting a video signal it can display.

UNLESS I plug the HDMI cable to the Dell monitor into the Mac mini. When I do that I get a normal image again.
The Dell monitor doesn't have to be powered up or switched on. It can be unplugged from the mains...
But the HDMI cable has to be plugged into the Dell's input socket.
Only then can the 5K monitor display an image - with SS>Displays detecting the Dell monitor even though it is unpowered and off.

Obviously the thing to try would be to completely uninstall BD, but there doesn't seem to be an option.
The screen dialogue layout of BD V3.5.5 seems to be completely lacking any of the buttons that a Google search brings up for previous versions? There is just a single Quit option on the ... option at the bottom. No Uninstall procedures?
Edit: OK Found a Reset button, Tool Icon>Application>Advanced settings & privacy drop-down.
It doesn't do anything to help.
Neither does deleting ~Library/Preferences>BD.

@waydabber Is there anything I can do apart from doing a complete MacOS reinstall?
Even with that I am worried about migrating the problem back when I recover the backup...

Thank you.

EDIT:
SOLUTION:
BD menu bar icon > Tool wheel icon at bottom > Displays > Overview > Additional Setting Drop-down > Reset All Display System Settings button (at bottom). 👍

 

[Bigwaff]

Is there anything I can do apart from doing a complete MacOS reinstall?
Even with that I am worried about migrating the problem back when I recover the backup...

The best way to get technical help or directly contact the developer is through the app's Discord channel.

 

[joevt]

Can you use screen sharing from another Mac or iPad and use that to select a different mode for the display on the problem Mac?

 

[PaulD-UK]

@joevt @waydabber
As I explained, connecting an HDMI monitor has given me full, normal, access to the M4 Pro mini.
Everything works as it should on both monitors when the additional HDMI monitor is connected.

I can 'select a different mode for the display' (carefully!!! trying not to make the problem worse?)...

I can disable or reenable Better Display.
I can attempt to uninstall BD, and trash its Pref file.
I can reinstall BD.
Boot in Safe or Normal mode.

But the problem remains.
When I disconnect the HDMI cable the 5K monitor fails, and after a normal (visible) MacOS boot, the monitor then only shows a black raster, with backlight behind.

So, what settings (to MacOS?) should I try to change?

 

[Bigwaff]

Does your 5K DIY monitor have a hardware reset on the board?

 

[PaulD-UK]

@Bigwaff
No reset option, but the monitor functions absolutely normally when connected to any other Mac or iPad.
So it’s some sort of MacOs corruption on the M4 Pro mini.

I’ve been reading through the BD onscreen info to get a better understanding of the App, and I’ll try Discord when I’ve got through it all.

 

[waydabber]

Hi @PaulD-UK - if the issue happens only with one display connected, then it might be a display layout related issue (maybe a wrong display mode is being set). I simply recommend resetting the system display settings. You can do so here:

Alternatively here are the steps you can perform via Terminal to reset all display configuration stuff in macOS (and BetterDisplay):

Safe mode, app reset, app removal

Unlock your displays on your Mac! Flexible HiDPI scaling, XDR/HDR extra brightness, virtual screens, DDC control, extra dimming, PIP/streaming, EDID override and lots more! - waydabber/BetterDisplay

github.com

Let me know if this does not work!

 

[Fishrrman]

If you need to remove betterdisplay, I would try this routine.

You will need 2 apps:
- AppCleaner
and
- EasyFind

First, open AppCleaner and use it to remove the obvious files from BetterDisplay.
(It found 3 files for me).

Then, open EasyFind.
Set it up as follows:
Search for - files and folders
Operator - any word
Comparison - ignore case
Include - invisible files and folders.

Then, enter "betterdisplay" into the search bar, and select your boot volume on the right (should be default setting).
Then click the "magnifying glass" to begin the search.

It returned 3 folders and a binary cookies file for me.
You can get rid of all of them.

Now, shut down and reboot.
That should do it.

But as others have mentioned, a reset of betterdisplay may resolve this.
If that doesn't work, then I'd try a "removal and re-install"...

 

[PaulD-UK]

@waydabber
The Reset All Displays button in your image did indeed work. Back to normal, thank you. 👍

Despite working my way through the online drop-downs for two days, I had missed this.
So for anyone else in this position, this is the solution!

https://forums.macrumors.com/attachments/1746711063437-png.2509100/

 

[joevt]

@joevt @waydabber
As I explained, connecting an HDMI monitor has given me full, normal, access to the M4 Pro mini.
Everything works as it should on both monitors when the additional HDMI monitor is connected.

I can 'select a different mode for the display' (carefully!!! trying not to make the problem worse?)...

I can disable or reenable Better Display.
I can attempt to uninstall BD, and trash its Pref file.
I can reinstall BD.
Boot in Safe or Normal mode.

But the problem remains.
When I disconnect the HDMI cable the 5K monitor fails, and after a normal (visible) MacOS boot, the monitor then only shows a black raster, with backlight behind.

So, what settings (to MacOS?) should I try to change?

My suggestion was to use screen sharing so that the setup remains as a single display.
I think each setup or arrangement of displays might get its own settings? Therefore, you need the single display setup to fix the single display arrangement problem.
Anyway, this suggestion is just another thing you can try if the problem happens again.

 

[waydabber]

Yes, the suggestion of @joevt should work as well.

The suggestion of @Fishrrman would not work in this instance, as the problem is not with BetterDisplay but with the display mode stored for the one-display layout in some of the system files of macOS. Reinstalling, resetting, removing BetterDisplay will therefore not fix this problem (note: the app can simply be removed by moving it into the trash, it does not have any additional daemon or hidden process running that must be uninstalled separately, so AppCleaner is not particularly needed - all it might do additionally is to remove the userdefaults config file and the license info from under ~/Library/Preferences, but these are totally inert stuff without the app bundle present and the best practice for macOS is just leave these there in case of a future reinstall).