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September 25th, 2021 02:00

U3821DW, DDM for macOS not working

I have U3821DW (Firmware M2B101) which is on the supported devices list for the DDM for macOS. So I installed this (just released) DDM (Dell Display Manager) macOS., A00) on both my M1 Mac's. The M1 Mac's are supported and both Mac's are up to date, running the latest macOS Big Sur (v 11.6.)

  1. M1 Mac Mini - Connected via (Original) HDMI1 + USB-B upstream cable 
  2. M1 MacBook Air - Connected via (Original) USB-C cable

When I start the App I get a pop-up message (please connect a supported monitor) with a notification message about USB-C or USB-B or DDC/CI or firmware:

Screenshot 2021-09-25 at 11.14.00.png

But all requirements are satisfied, and I can't find any firmware update for the U3821DW anyway!? 

- DDC/CI = on
- Using Original cables
- Cables inserted properly
- No Docking in between
- Bot systems restarted

I also read the Dell Display Manager on Mac User's Guide, but everything seems to be fine and it should working, but it is not!? 

Community Manager


54.2K Posts

September 28th, 2021 08:00

U4320Q, U4021QW users should start new threads. This thread is only for U3821DW.

U4320Q, DDM for macOS not working
On the new thread, note if you have installed the latest U4320Q macOS firmware update M2T104.

U4021QW, DDM for macOS not working
On the new thread, note if you have installed the latest U4021QW macOS firmware update M2T102.


* Close DDM on both PCs
* Download /install this U3821DW macOS firmware update M2B105. When done, test DDM

6 Posts

October 1st, 2021 01:00

Hello DELL-Chris M

I can confirm that after the firmware update my devices are smooth sailing with DDM.  

Tnx for those involved fixing it.

Screenshot 2021-10-01 at 09.52.43.png

6 Posts

September 25th, 2021 07:00

In lieu of DDM for macOS I have been using the opensource tools MonitorControl and Rectangle the past months. Both make it possible to control screen brightness, volume and snap windows; working fine from both my Mac's and MC is capable to recognise the screen via DDC/CI.

But it would be nice to have DDM to control the KVM functionality of the Display!


Screenshot 2021-09-25 at 16.30.56.png

Screenshot 2021-09-25 at 16.29.30.png


Don't understand why for the same display, from the same Mac, the DDM software can't recognise the Display!?

Screenshot 2021-09-25 at 16.32.12.png

8 Posts

September 25th, 2021 10:00

I get the same error message on my M1 Mac Mini with a U4320Q over USB-C. Upgraded the firmware, but no change.

I also tried using a USB-C to Mini DisplayPort cable. No luck there either.

So it's not just you...

8 Posts

September 26th, 2021 13:00

If you take a look at the Diagnostic Report (hold down Shift key and Right Click on DDM) you can see the application trying to find a DDC/CI compatible monitor via USB and failing.

2021-09-24 11:27:06.663 DEBUG -[AppDelegate applicationDidFinishLaunching:]:204 - ======DDM Start Launching=======

2021-09-24 11:27:06.807 DEBUG -[AppDelegate applicationDidFinishLaunching:]:275 - Set AutoLaunch to 1 Good

2021-09-24 11:27:08.046 DEBUG -[AppDelegate checkNewVersionWithNotification:]:4662 - DDM Newest version = ; Current version =

2021-09-24 11:27:08.047 DEBUG -[AppDelegate checkNewVersionWithNotification:]:4676 - DDM is up-to-date

2021-09-24 11:27:08.049 DEBUG -[AppDelegate GetDisplayInfo]:3515 - GetDisplayInfo NOT in MainThread

2021-09-24 11:27:08.168 DEBUG -[USBSDK init]: 47 - USB SDK Version = 320

2021-09-24 11:27:08.289 DEBUG -[USBSDK init]: 88 - USB GetAvailableMonitors 1 tries

2021-09-24 11:27:08.343 DEBUG -[USBSDK init]: 88 - USB GetAvailableMonitors 2 tries



2021-09-24 11:27:10.390 DEBUG -[USBSDK init]: 88 - USB GetAvailableMonitors 39 tries

2021-09-24 11:27:10.444 DEBUG -[USBSDK init]: 88 - USB GetAvailableMonitors 40 tries

2021-09-24 11:27:10.444 DEBUG -[USBSDK init]: 93 - --- GetAvailableMonitors failed. SDK not ready ---

2021-09-24 11:27:10.445 DEBUG -[DDCCtl LoadUSBDisplays]:740 - SDK not ready

2021-09-24 11:27:11.237 DEBUG -[AppDelegate DDM_ini]:1589 - DDM_ini queryingDisplayInfo = 1

2021-09-24 11:27:11.237 DEBUG -[AppDelegate InitUI]:1774 - InitUI

2021-09-24 11:27:11.237 DEBUG -[AppDelegate InitUI]:1775 - pending operation count = 0

2021-09-24 11:27:11.237 DEBUG -[AppDelegate InitUI]:1828 - No monitors have DDCCI.

2021-09-24 11:27:11.238 DEBUG -[NotificationCenter showNotificationWithTitle:Content:Log:Delay:]_block_invoke: 44 - Local Notification succeeded

2021-09-24 11:27:17.924 DEBUG -[AppDelegate statusOnClick]:1157 - statusOnClick image = DDM-notfound


6 Posts

September 27th, 2021 07:00

That's exact what I see in my log file too..

2 Posts

September 27th, 2021 08:00

I have the same error on my Macbook Pro (M1), BigSur 11.6 and Monitor Dell U4021QW. The Macbook is over USB-C (Original Cable) connected to the monitor and DDC/CI is ON.

8 Posts

September 27th, 2021 10:00

In another thread on a very similar topic, I saw Dell respond with "that monitor is not compatible with Dell's Monitor SDK", even though the poster's monitor is listed as compatible. 

I am wondering if maybe DDM was rushed to market without complete testing, or the accompanying documentation is incorrect. It lists my monitor (U4320Q) as compatible.

I'll continue to use a PC linked up via USBC (DDM works) and Mac Mini via HDMI, but I was hoping that when Dell said they would be releasing DDM on Mac that it would support the same monitors as the PC.

4 Posts

September 29th, 2021 00:00


I had the EXACT same problem with my U4021QW. After you install the firmware package and DDM, check your applications file and there should be a folder called Dell. In it there is monitorfirmwareupdater app install it and your DDM should be working. Why on earth does it say firmware installed and say it may take up to 30 minutes after you install the firmware package, leading people to waste so much time finding the solution? You guys seriously need to update your instructions on how to update the firmware on macOS. I went through your whole page, FAQ, and readme files and nothing was mentioned. You guys need to fix it so people don't get confused.



25K Posts

October 1st, 2021 02:00

Happy to hear that. In the future, if there are any other issues, feel free to reach out to us, we are here to help.



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