f.lux reporting 1900K, but screen is still at 6500K.

  • I'm having an issue where it isn't working at all, my OS is Windows 10 Enterprise Insider Preview (Build 18305). I also reinstalled it and it didn't work in fixing it.

  • I upgraded to Build 18305.1003, and even made sure that the full color range was turned on (I restarted). Same issue.

  • Microsoft Night Light might be enabled and overriding f.lux.

  • Windows Night Light is not enabled.

  • Damn. Hmm. I think (but I'm not certain) I had this happen to me on my computer (and I have Windows 7). If I can recall what caused it and how I fixed it, I'll post again. That's the best I can do at the moment.

  • Same issue here. 10 Pro IP 18305. f.lux launches, stays in the tray, shows notifications, but won't change colors. Windows Night Light isn't working either.

  • Do you have any HDR options on? Or an HDR-capable monitor?

  • Also can you post f.lux options > Driver info?

    One report of this so far included a recent NVIDIA update, so I'm trying to tell whether this is 18305 or NVIDIA.

  • "Night Light functionality has been impacted by a new bug in this build. Root cause is underway, and we expect to have this fixed in an upcoming build."


  • I have the same problem after the update W10 Pro & W10 Home Insider preview. Windows Night Light is disabled

  • Same Problem. Windows 10 Enterprise Insider preview 18305. Was working fine in 18298. I'm on Intel HD 510 btw, so probably not an issue with NVIDIA

  • @herf
    Sorry for a late response! here's the info. Currently it seems to be semi-working, as the color temperature is changing as expected, although hotkeys, disable/enable, exiting f.lux or dimming is not working.

    Also I posted this in Reddit around the time of my original comment and someone said there "Night Light and F.lux not working in 18305 is a known issue" without specifying known to whom.

    f.lux 4.86
    None of displays is HDR capable
    Night Light is turned off
    "V223HQL (Digital)" is 3 FHD panel spanned using NVIDIA Surround

    Intel Corporation Intel(R) HD Graphics 3000 (20160519)
    NVIDIA NVIDIA GeForce GTX 1070 (20181129)

    V223HQL (Digital), 1440 x 290mm, built 2013
    R=0.639648 0.330078
    G=0.299805 0.599609
    B=0.150391 0.059570
    W=0.313477 0.329102

    sRGB gamut: 100%, AdobeRGB gamut: 64%

    Generic PnP Monitor, 337 x 270mm, built 2005
    R=0.634766 0.336914
    G=0.287109 0.613281
    B=0.143555 0.085938
    W=0.312500 0.329102

    sRGB gamut: 93%, AdobeRGB gamut: 65%

    NEC LCD93VXM, 376 x 301mm, built 2009
    R=0.640625 0.336914
    G=0.303711 0.620117
    B=0.140625 0.073242
    W=0.313477 0.329102

    sRGB gamut: 93%, AdobeRGB gamut: 66%

    Windows Build: 18309

  • temporary fix here:

    We are waiting on MSFT for the real fix.

  • Now the issue came back in Build 18850, but Windows night light still works fine.

  • Well, there does not seem to be an issue anymore, but I have noticed something new in Build 18860, where the UAC and lock screen are correspondingly colored by the f.lux colors correctly, which is nice.

  • Now it is quite the opposite, where f.lux is reporting 6500K, but screen is still at 1900K. It even persists when f.lux is closed, this issue has only shown up once I woke up my computer from sleep mode, and it has not happened until this one time in Build 18865.

  • I fixed it with a simple restart. Sorry for the inconvenience.

  • I can confirm that coming out of sleep mode and flux breaking happens for me as well. By breaking I mean that the screen temperature just doesn't change. Flux v4.100 A reboot helps.

    NVIDIA NVIDIA TITAN V (20181129)

    Generic PnP Monitor, 518 x 324mm, built 2018
    R=0.660156 0.332031
    G=0.301758 0.613281
    B=0.150391 0.063477
    W=0.313477 0.329102

    sRGB gamut: 100%, AdobeRGB gamut: 69%

    Generic PnP Monitor, 518 x 324mm, built 2018
    R=0.660156 0.332031
    G=0.301758 0.613281
    B=0.150391 0.063477
    W=0.313477 0.329102

    sRGB gamut: 100%, AdobeRGB gamut: 69%

    Windows Build: 17763

  • Ok - I am running 17763 on the NVIDIA "1735" build but I'm on a Pascal and not a Volta series.

    Does moving the sliders within f.lux stop working entirely? I would recommend trying a newer driver version, but I don't know which one. :)

  • @herf Moving sliders "physically works", meaning I can grab the temperature slider and move it back and forth, but there is no effect on the screen at all.

    I updated to the latest driver, 425.31, for now it seems Flux is working through a sleep (I didn't even restart between the driver update, and the following sleep). Will keep you posted!

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