macOS Monterey 12.x upgrade instructions for existing EFIs running pre-Monterey macOS

[LeeBinder]

First of all, consider wisely if at this rather still early point it would really be a smart decision to already run this young OS as your main production OS, esp. because of apps which are lacking compatibility, or even Apple making it increasingly difficult for certain apps to remain fully functional. Example: TotalFinder (can not be made to run in Monterey, see their statement here).

In that light, therefore recommended procedure for highest compatibility: clone your existing macOS install to a new APFS volume in the same container (shared = saved space) and upgrade THE CLONE to macOS Monterey, keeping your current macOS as your main production OS; or do a fresh install to a new APFS volume to test Monterey.

Update instructions per boot loader

OpenCore:

1. update OpenCore to the latest version (tested with 0.7.5)

2. update all kexts to their latest versions, easiest with either Hackintool or Kext Updater

3. update OpenCore Configurator

4. download Resources.zip, unpack and replace your EFI/OC/Resources folder with the extracted

5. open your OC config.plist with OpenCore Configurator. In the Misc. section, configure like this:

   

6. Save and reboot

7. install macOS Monterey as per recommendation above

Clover:

1. Update Clover to the latest version (tested with 5142)
2. see above
3. Reboot
4. see bullet-point 7. above

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Synchronization with whatnameisit's now archived repo is scheduled to occur soon.