#18457 (Bug) Installing profile darkened screen, froze iMac, cannot access drives

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Closed as Invalid
Component: DisplayCAL 3.8.2
Created by Deb H

Last modified

I downloaded DisplayCAL yesterday to work with my old i1 Gretagmacbeth colorimeter. It seemed to work.
My first calibration ended with an error message after the Mac fell asleep.
The second time I paused the process and later resumed the calibration.
When I clicked to install the new profile, the screen went dark and the computer has not worked since.

Nothing I have tried — restarting in various modes, re-installing OS — has worked. Cannot access any part of the Mac. A second monitor shows the dock but is non responsive, except for some key commands.
In short, nothing works.

No log files since I can’t access anything.

5 comments on “Installing profile darkened screen, froze iMac, cannot access drives”

  1. This isn’t related to DisplayCAL or the profile. An ICC profile is just a small binary file on your computer, it does not (and cannot) affect how your computer functions.

  2. And yet, that’s what happened.
    I left the machine alone for about 36 hours. When I restarted, the pulldown menu bar  was visible on the 2nd monitor, and e v e n t u a l l y  I got a cursor arrow to appear.  At that point it was a simple matter of system prefs and selecting a different color space.
    Now things are back to normal, but the moment of installation did trigger an entirely dark and blank screen and generally slow/non-responsive system. It was instaneous, so I don’t know what else it could be.


  3. That sounds like some kind of thermal problem, and not at all what you initially reported (i.e. that OS reinstallation did not help). Anyway, without having access to the profile, this is moot.

  4. The origin of the darkened screen seems to be that the monitor went to sleep at times while the measurements were being taken, resulting in a very dark profile. Why the machine became so unresponsive is still unclear.

  5. Re Profile that caused system to hang…

    The display subsystem is a cornerstone of computer architecture, with a complex nexus of hardware and software.

    The whole Mac UI is color managed these days.

    And… Sleep functionality is a notorious system bugaboo that has plagued Mac (PC) reliability for decades, maybe since its invention.

    This next point is totally anecdotal, but as I’ve been experimenting with DCaI switching  profiles in System Prefs > Displays : Color causes a storm of disk activity and very high CPU load for a couple seconds. Various apps do screen updates and UI takes a second to settle. So the profile maybe a small bit of data, but it’s causing a surprisingly big effect when it’s changed—this is on several Macs running 10.14.5 Mojave in dark UI mode.

    So profiles and therefore DisplayCal cannot be merely waved off as an insignificant input to system behavior.

    Plus, idea that a profile’s small data footprint in and of itself makes it insignificant to system behavior is easily seen as absurd when you realize that a computer boots and comes to full working glory from a few bytes of a branch instruction and an address in the boot sequence.

    I have no answer to why it froze, but it’s not surprising that it could for no other reason than a display profile. and it’s possible a malformed profile could cause a system crash or be a vector for malicious code—I’m not impugning anything OMG :::)))

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