Question: easy access to old Mac OS system for build?

Recently we hit an issue that the prebuilt Mac OS binaries don’t work for old Mac OS, the installation still works but it rebuild the whole world which makes the disk space quite large,
seem more details here:

Either I revert my Mac OS or is there an easy way to access the old Mac OS for free?

Assuming you have an external drive, you could try to install the older Mac OS version on it.
I’ve never tried it myself so this is pretty speculative but you could try the following:

  • Download MacOS High Sierra (
  • Launch the installer on select the external drive as the install location (the external drive will probably require to be formatted to the proper filesystem)

If your Mac version is too recent, there’s a good chance that the installer refuse to continue. In this case you would have to create a bootable installer (as explained here, but in this case you would need 2 external drives (one for the installer, the other as the install location)

Hi, I have a working macOS High Sierra 10.13.6 here. I’ve tried to build the rescript-compiler.git repo. Apart of wome camlp4of warnings (and erorrs?) I think it went fine. Would you like to download the entire built repo with all the binaries?

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Hi Ben, thanks for the help, it means a lot. camlp4 warnings are fine. The thing is that I need to do it regularly (instead of one time effort), thanks again!

So I found my ancient Mac Book Pro, it’s great that it still works, I will close this thread, thank you all for the offer!