unknown or unsupported macOS version: :dunno (MacOSVersionError)

[hongdeyuan]

I try to brew install redis;
has a error:
unknown or unsupported macOS version: :dunno (MacOSVersionError)？ why?

[FnControlOption]

What is your output for brew config and brew doctor?

[hongdeyuan]

resolved

[gromgit]

For posterity: https://eclecticlight.co/2020/08/13/macos-version-numbering-isnt-so-simple/

[gromgit]

@hongdeyuan , just to confirm: When you unset SYSTEM_VERSION_COMPAT, did brew config and brew doctor suddenly start working? Or did you have to do something else?

[gromgit]

resolved

@hongdeyuan , how did you resolve your issue? There's a PR that may have to be changed depending on the answer to that question. Thanks much!

[beck]

Here because I'm getting similar issue after upgrading to Monterey. For both brew commands output is the same:

/usr/local/Homebrew/Library/Homebrew/os/mac/version.rb:32:in `block in from_symbol': unknown or unsupported macOS version: :dunno (MacOSVersionError)

Updating homebrew was the fix for me

[beck]

Same issue after updating to Monterey. Updating homebrew fixed the issue, but I needed to first:

git -C /usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask fetch --unshallow

Then I was able to:

brew update

[Gen-i-soft]

i solved the problem : brew update-reset

[cht-wtag]

@beck brew gives me: fatal: --unshallow on a complete repository does not make sense, please, could you tell me what I should do.

You have to do it in a different directory:
git -C /usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask fetch --unshallow

[dvag-lukas-rybacki]

Thanks @beck , this worked for me. Oh i also run: git -C /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core fetch --unshallow

[mghazanfar]

I noticed that the correct address is given with the error so everybody has to use that corresponding address.

[dominiceden]

@Gen-i-soft thanks, this was the only thing that worked!

[iwangchuanli]

Hi,The problem is because Apple released a new system：monterey
please try find /usr/local/Homebrew/Library/Homebrew/os/mac/version.rb.
and then vim version.rb,add monterey

SYMBOLS = {
	monterey:    "12",
        big_sur:     "11",
        catalina:    "10.15",
        mojave:      "10.14",
        high_sierra: "10.13",
        sierra:      "10.12",
        el_capitan:  "10.11",
        yosemite:    "10.10",
      }.freeze

[techiechap]

Well i tried modifying the /usr/local/Homebrew/Library/Homebrew/os/mac/version.rbrb as suggested by
@iwangchuanli and end up with below error
brew info test

Error: No available formula or cask with the name "test".
==> Searching for a previously deleted formula (in the last month)...
Warning: homebrew/core is shallow clone. To get complete history run:
git -C "$(brew --repo homebrew/core)" fetch --unshallow

Error: No previously deleted formula found.

[carlocab]

Modifying the source of brew is a really terrible idea if you don't know what you're doing. At minimum, you'd want to be very proficient with git before trying it.

[techiechap]

Modifying the source of brew is a really terrible idea if you don't know what you're doing. At minimum, you'd want to be very proficient with git before trying it.

thanks i agree but i thought its quick fix adding just the "monetery" mac os version would solve, i did remove and made the original file as it is, looking for the fix

[Bo98]

I fixed the error here over a year ago (February 2021), so you should look into why your brew is severely outdated.

Does brew update-reset work? Does it print any errors? If it completes without errors, what does git -C "$(brew --repo)" remote get-url origin output?

[techiechap]

Thanks i tried to use git -C "$(brew --repo homebrew/core)" fetch --unshallow but it stuck up for a while then i had to use these two git -C /usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask fetch --unshallow git -C /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core fetch --unshallow

then executed brew outdated which gave me a bunch of outdated stuff, then finally brew upgrade

[techiechap]

i tried to use git -C "$(brew --repo homebrew/core)" fetch --unshallow but it stuck up for a while then i had to use these two git -C /usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask fetch --unshallow git -C /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core fetch --unshallow

then executed brew outdated which gave me a bunch of outdated stuff, then finally brew upgrade

[4EverEndeavor]

I ran into this issue and was able to fix today. MaxOs Monterey
First, I uninstalled brew:
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/uninstall.sh)"
Then, I did an alternative installation in /opt/homebrew following the instructions here
https://docs.brew.sh/Installation
Hope this is helpful for some one.

[christiandufner]

wow that was unthinkably simple!
I just installed the latest *.pgk from: https://github.com/Homebrew/brew/releases/

THX

[EricWong1994]

what are you talking about ? ? ?

[xiaohuilam]

Email auto reply, maybe.

[deveshlashkari]

I faced a similar issue on my Mac (Sonoma)
Error: unknown or unsupported macOS version: :dunno
I just ran :
brew update-reset and it worked flawlessly.

[fetterollie]

brew update-reset also worked for me on macOs Sonoma 14.3.1

[akankshasaxena]

Thanks folks, brew update-reset worked for macOs Sonoma 14.4.1 too

[IanaKain]

brew update-reset worked for me as well
Thanks!

[BaseEncoded]

+1 to this answer, it needs more vis.

[gbrindisi]

if brew update-reset does not output anything, make sure you have xcode installed with xcode-select --install