[R-SIG-Mac] macos 26 considerations

[Duncan Murdoch]

On 2026-02-22 12:15 p.m., Bill Evans wrote:
> Thank you Prof Murdoch, that’s the context I was looking for. When 
> xquartz did not work for you in Tahoe, did you try homebrew or macports’ 
> “xorg-server” and “xinit” packages? The pair is a documented alternative 
> to xquartz, and if I believe what I read, those are supposed to work on 
> tahoe.

No, I didn't try those. I was on a very tight schedule, and I didn't 
have time to experiment.  But from what Gabor wrote, maybe Xquartz is 
working again with the latest Tahoe.

For what it's worth, I did a quick search today and found this advice 
against Tahoe for some neuroimaging people:

  
https://discuss.afni.nimh.nih.gov/t/re-macos-tahoe-and-xquartz-issues-for-afni-users/9227

As of Jan 21 they were still advising against the upgrade, though some 
of their problems had been addressed.

Duncan
> 
> Some follow-on discussions for the crowd:
> 
>  1.
> 
>     Does there already exist or can we make an FAQ or caution-page for
>     upgrading to tahoe? I suspect I’m not the only one who has
>     considered taking the upgrade, and since downgrading is not easy
>     (likely “not possible” for some), I think having a reference to this
>     on |mac.r-project.org| would be a “Really Good Thing (tm)”.
> 
>  2.
> 
>     I believe XQuartz is for displaying the plot canvas when not using
>     RStudio or Positron. If we can’t have xquartz, what else are we
>     losing? As an incomplete alternative, for many plots one could use |
>     httpgd| (if/when they fix some bugs) or other “immediate” file-based
>     rendering, though I think this does not work for |rgl| (perhaps others).
> 
>  3.
> 
>     The webpage says /“R 4.6.0 CRAN arm64 builds use macOS 14”/, which
>     further concerns me wrt compatibility and package availability. I
>     know it’s a complicated topic, perhaps it’s too soon to say with
>     authority that tahoe is going to be safe for R and for compiled
>     binary packages.
> 
>     This is likely related to Xcode and the MacOS SDK; I believe Tahoe
>     “really wants” Xcode 26 and the 26 SDK, and I believe (no refs atm)
>     that older versions can be problematic on Tahoe. I understand
>     backward compatibility is always a concern, perhaps that is why the
>     dev build is targeting macos 14, xcode 14.3, and 14.4 SDK. There are
>     a lot of talented people working tirelessly (and often thanklessly)
>     on this process, the more I learn the more I am thoroughly grateful
>     for their knowledge and efforts.
> 
>     Is there yet a clear pathway for advancing to more up-to-date
>     versions? Or is it still murky and peppering the devs with questions
>     like this is just accelerating their “early retirement”?
> 
>  4.
> 
>     Are all of my xcode/sdk questions above “moot” when using the
>     RStudio or Positron IDEs? They are not (afaict) using x11 to render
>     their plots, though I’m not sure how they show rgl-based plots.
> 
> Thanks all, I appreciate your time.
> Bill
> 
> On 2026-02-22 08:50, Duncan Murdoch wrote:
> 
>> On 2026-02-22 10:40 a.m., Bill Evans via R-SIG-Mac wrote:
>>> I’ve been holding off upgrading to MacOS 26 for many reasons, most
>>> related to yet-unsubstantiated concerns about R. Because it’s a new ABI,
>>> I suspect the process would be similar to a major/minor release in R:
>>> update the compile chain then re-install all packages. Is there a strong
>>> recommendation for or against this upgrade? Are there safe or at least
>>> less-risky pathways for upgrading the OS? Is R-devel regularly tested
>>> against 26? Are there known unresolved problems, such as “package xyz
>>> does not currently work”?
>>>
>>> FTR: I’m currently on macos 15.7.4 using R-4.5.2, and there is nothing
>>> inherently broken. I don’t have a /need/ to upgrade to 26 atm but fear
>>> at some point that some tool I use (be it Parallels or something else)
>>> may eventually require 26 for some or all of the desired functionality.
>>> I’m just planning ahead (and holding back two colleagues, also on
>>> macos-15.7).
>>
>> I upgraded in the fall, and found that XQuartz didn't work, and its 
>> maintainer had stopped working on it.  Since I was planning some work 
>> on rgl that needed XQuartz, I downgraded and I'm still on Sequoia 15.7.2.
>>
>> You should be aware that downgrading isn't easy:  you need to create a 
>> bootable external disk, reformat your main drive and restore from a 
>> backup.  I did it and didn't lose anything, but it wasted a day or so, 
>> during which I wondered whether my backups were really as complete as 
>> I hoped they were.
>>
>> Duncan Murdoch
> ​