DELL U3818DW screen no longer supported.

I followed the "alt" suggestion above too ("alt" is the "option" key on the MacBook keyboard), and chose the 3840 x 1600 (low resolution) option, which is the U3818 native resolution. This seemed to restore the display to the previous resolution I used with Mojave. If any anomalies are observed with this setting, please post them here.

btw, while you still need to use the "alt"/"option" fix to pick the right resolution, if you use USB-C/Thunderbolt instead of HDMI you don't get 3840x1600 as a "low resolution" option but at full resolution. I don't see much of a difference between the two but i don't do much video work.

I have the same issue going through HDMI cable. I'm going to try and order a DisplayPort to Mini-DisplayPort cable and see if it does any better. One trick I just learned is in your preferences > Display, set the Resolution to "Default for display". Then hold down the ALT key and select the "Scaled" option in preferences. This should give you some more options for resolution.

I found that you can get it to work by using Parallels Toolbox, using the tool to change resolution to suit the monitor.

otto260 Said:

”My widescreen worked fine in Mojave.

Looks like it is not supported by Catalina. The highest resolution available is 1920x800, which is way lower than my screen is capable of.[...]”

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Inform Apple of This Using Feedback:

I am not aware of any solutions at the moment. But I had the same issue, and then downgraded for a while.

As a result, I reported it to Apple using the Feedback site. I recommend you do the same, that way Apple knows more of what’s going on, knowing what bug to fix and the like.

The Link: Feedback - macOS - Apple

Select:

• “Feature Request” for the Feedback Type
• ”Accessibility” for the Feedback Area

You are welcome.

You can always give feedback on lots of items. You might not get a direct reply back, but at least their engineers will know what their customers/users are expecting and what they need to fix.

Go here: https://www.apple.com/feedback/

here's something REALLY odd. when i used the monitor as a second display it worked great. But once i closed the lid (i use a henge dock) it stopped working. The alt trick works perfectly though

I indeed get it when my screen is plugged with a USB-C adapter.

But when I use the WD15 Dell Dock, this resolution is not proposed.

@apple, I love the new OS. It's great and kudos for always pushing the boundaries. That said, going public with an OS that doesn't support a popular, and expensive monitor seems like an oversight. There is a ton of buzz and recent reviews on YouTube about this monitor so it's not a phased out, obsolete model. We understand that you can't support everything forever, but the U3818DW should be supported.

Love you but this has been a poor user experience.

Dell U3818DW seems to work only at a 1920X800 resolution in MacOS Catalina, not the much higher resolution the monitors capable of. Any solutions?

Thank you for posting! I experienced the same thing. Hopefully Apple will fix the anomaly soon.

I'm having the same problem. I wonder if it's a change in how they handle the HDMI connection. That's almost exclusively how I use this now so problematic if it's been removed as a functionality.

You then can control both monitors.