Q: macOS Sierra no longer supports ultrawide monitors?

my problem with my LG UltraWide monitor now, is that it just stretch the 1920x1080 instead as on el capitan where It could go to 2560 x 1080, Seems like Apple just ditches UltraWide support

I told the german technical support hotline about the problem. They said it will most probably be fixed in a future update. To assure this, I would recommend people with the same issues to give Apple a call.

Here another LG ultra wide user

After upgrading to Sierra OS. The native resolution of 2560x1080 is no longer an option!

It believes that 1920x1080 is the native resolution of this monitor. Now I got black bars on both sides.

… and today I got a call back in order to gather some system log files for the technical engineering team. Let´s hope they will fix the issue soon.

Let's hope!

Same issue here with an LG Ultrawide.  I called Apple today and they told me it is a known issue that will be fixed in an update soon.  They had me put this into the terminal and reboot my computer with no luck, but some have had luck with this if you want to give it a try:

sudo defaults write /Library/Preferences/com.apple.windowserver.plist DisplayResolutionEnabled -bool true

I have the same problem on a AOC 3440x1440.  The "best" option I get is 1080p.  Excruciating.

I'm having the same issue here, I cant believe they shipped the new OS with that bug. What is going on Apple? Did you QA before release?

I was able to fix the problem using the tool SwitchResX by following the steps at

http://terrislinenbach.blogspot.co.uk/2015/12/running-lg-29um57-p-on-old-macbook -pro.html

But SwitchResX is a paid solution, so Apple should fix that soon.

The issue is not Ultrawide-monitor specific. Happens also with my 27" Acer Predator that worked just fine with El Capitan and older macOS. Very annoying as I use the MacBook for work and development. I did not get the 2560x1440p resolution when holding down the option-key. And no mater what other resolution I choose, the screen itself is very small in the middle, with black bars around, does not scale one bit.

So two problems after upgrading to Sierra:

1) Cannot choose proper resolution (2560x1440)

2) Does not scale at all (no mater the resolution)

Created a bug-report with Apple, but still no reply... C'mon Apple, our eyes are bleeding here.

This fixed mine today!

I bought that app two days ago thinking about hacking this problem but I was not able to find the right combination.

Thank you so much!!

Now to wait for Apple for the right update.

Hello everyone,

I just saw this problem mentioned with at least one suggestion for a fix:

http://mjtsai.com/blog/2016/09/27/sierra-drops-hidpi-scaling-on-external-display s/

I found a way to fix this for my monitor!!

So everyone's using SwitchResX ($16), but I found that since my monitor supports a DisplayPort connection, I switched from HDMI to DP using this cable ($9).

The problem is gone, and I'm back to being able to use my monitor.

I know this can't help anyone without an HDMI alternative, but it seems like Apple just dropped support for native resolution on high-res monitors over HDMI.

For those who want a quick primer on display ports: https://www.youtube.com/watch?v=f38sotYHqtA

(updated video link to a newer video)

P.S.  I just found that some minor input lag when watching high-res video full screen is no longer present after switching away from HDMI.

Ok so I managed to fix the problem by installing the latest Beta of macOS Sierra (10.12.1 Beta 2). After installation I did a reboot, went to display options and under Scaled I got all the resolutions supported my the monitor.

So, Apple knows about the issue, and has a fix comming for it!