Installing old root version

HI everybody,
I am trying to install root 6.24 via homebrew and tried:

brew install root@6.24.06

Sadly, this does not work. I am not an experienced user and therefore I need homebrew for the installation. Can anyone help or tell me, if it is even possible to install an older version.


(MacOS 12.2.1)

See other solution (wget) than homebrew here: Installing ROOT - ROOT

Thank you for your answer. Unfortunately there seems to be no version of root 6.24 for MacOS 12.2.1. Can I simply install a version for an older MacOS?

I tried to install root 6.24 via the download as proposed but that does not seem to work.

Yes there is no compiled version of ROOT for MacOS 12.2.1. See Release 62408 - ROOT
At that time MacOS version was 11.7.
You can recompile root from source as explained here:
Installing ROOT - ROOT

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@couet Thank you for your answer. I am trying to do this and recompile root from source. Sadly this leads to the following error when building with cmake:

<<< cling interactive line includer >>>: fatal error: module file ‘/opt/homebrew/opt/rootbuild/lib/Rint.pcm’ is out of date and needs to be rebuilt: could not read module signature

<<< cling interactive line includer >>>: note: imported by module ‘MathCore’ in ‘/opt/homebrew/opt/rootbuild/lib/MathCore.pcm’

Error: Module ‘MathCore.pcm’ failed to load.

Error: Error loading the default rootcling header files.

make[2]: *** [math/mathmore/G__MathMore.cxx] Error 1

make[1]: *** [math/mathmore/CMakeFiles/G__MathMore.dir/all] Error 2

make: *** [all] Error 2

What does this mean and can I solve this problem?

Can you post here the commands you typed ?


tar -xzvf root_v6.24.06.source.tar.gz 
mkdir rootbuild rootinstall 
cd rootbuild
cmake -Dbuiltin_glew=ON -DCMAKE_INSTALL_PREFIX=../rootinstall ../root-6.24.06
cmake --build . --target install

what about:

tar -xzvf root_v6.24.06.source.tar.gz 
mkdir rootbuild 
cd rootbuild
cmake -all ../root-6.24.06
gmake -j8

I got it to work with my commands now. Apparently there was just one file not correct, which got built again after deleting it. Now root 6.24 actually works, but I get one error and several info:

Error in TCling::LoadPCM: ROOT PCM /opt/homebrew/opt/rootinstall/lib/libNet_rdict.pcm file does not exist

Info in TCling::LoadPCM: In-memory ROOT PCM candidate /opt/homebrew/opt/rootinstall/lib/libASImageGui_rdict.pcm
(There are more info’s but they are the similar with different pcm candidates).
As root seems to be working anyway, this is not urgent, but I would still like to get rid of these messages. Do you know what to change?


is it where you installed ROOT ?
Have you sourced after the install ?
what gives you which root ?

This seems to be a leftover of a previous installation of ROOT (presumably from Homebrew) in /opt/homebrew/opt/rootinstall/.
Probably your ${ROOTSYS} environment variable is pointing to that directory instead of pointing to where ROOT is currently installed.

As @couet said, you could try sourcing bin/ from your install directory, as in:

$ source path/to/install_of/root_v6.24/bin/
$ root


The directory pointed out by @couet is were root is installed. I have sourced root by adding

source /opt/homebrew/opt/rootinstall/bin/

To the ~/.zprofile . And this is all working as root shows me that it’s version 6.24 and everything is running nicely. Therefore the problem is not urgent but it is a little bit annoying to get this error message every time I run root.
I also took a look and in the folder rootbuild/lib there is no file called libNet_rdict.pcm. Also make lib/libNet_rdict.pcm does not work, as the error message for that command is:

make: *** No rule to make target `lib/libNet_rdict.pcm’. Stop.

It seems that there might have been a problem during build of PCM files. As @couet pointed out, I would suggest limiting the number of parallel processes during build.

Maybe you can try removing lib/*.pcm files and let make trigger the rebuild of those

$ rm lib/*.pcm
$ gmake -j8

See related post here: WSL Build from source error: RInt.pcm is out of date \ cannot read module signature


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Unfortunately this does not solve the problem. However as everything I try to do with root seems to work anyway, I don’t think it is that necessary to solve this minor problem.
Thank you all for your help!

1 Like

Ok, but a clean reinstall should have worked. Very likely, as @jalopezg said, you may have some left over.

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