Not detecting any monitors on Mac Mini OS 10.15.7

[Don Smith]

I cannot get any monitors detected, but I used to.  I just switched two of my monitors for new ones and I wanted to calibrate them.

I am on Mac OS 10.15.7 (19H114) .  I found some tips in another thread, but my Argyll is in a different path ~/Library/Application Support/DisplayCal/dl/Argyll_v2.1.2/Bin ) this is where DisplayCal downloaded and installed it.  I run the dispcal -? the -? does not seem to be a valid argument.

bin % ./dispcal -D

get_a_display called with ix 0

Found 3 screens

CGDisplayIOServicePort returned error

dispcal: Error – Unable to open the default display

But DisplayCal does not show any of my 3 displays.  One is displayport, one HMDI and one is USB to HDMI (displaylink chipset).  I have calibrated with DisplayCal before, but I cannot today.  I have uninstalled and re-installed.

[Don Smith]

So no one has any ideas?

[Don Smith]

I sorted it out.  It turns out the DisplayLink Display Manager was blocking from reading the displays.  AllI had to do was unplug the one display that was using it (USB to HDMI) and then the other two displays were detected.  Since the two of the monitors are the same, I used the same calibrated profile for both.

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