When upgrading older computers with a pre-Mojave (MacOS 10.14) OS you will need to do two upgrades.

Upgrade #1 to Mojave (step 1 OR 2 below)

Upgrade #2 to either Catalina, Big Sur, or Monterey (Step 3 below) Do not attempt Monterey on a computer older than 5 years).

1. If you are upgrading from OS X 10.11: El Capitan to Mojave you will first need to change the date on your computer.

i. Launch Terminal

ii. Type in the following (you may cut and paste)

sudo date -u 0101121217

and press the enter key.

iii. Type in the following (you may cut and paste):

sudo jamf policy -trigger install-install-macos-mojave

You will be asked for your password.

iv. This will place the installer in your Applications folder and you can run it at will.

v. Run the installer that you have downloaded to upgrade to Mojave

2. To upgrade from macOS 10.12: Sierra or macOS 10.13: High Sierra to Mojave

i. Launch Terminal

ii. Type in the following (you may cut and paste):

sudo jamf policy -trigger install-install-macos-mojave

You will be asked for your password.

iii. This will place the installer in your Applications folder and you can run it at will.

3. Once you have Mojave, you can upgrade to Catalina, Big Sur, or Monterey:

Go into the Recovery Console by doing the following at Startup:

EITHER

A. Hold down either the Option/Alt-Command-R or Shift-Option/Alt-Command-R at startup to force macOS Recovery to boot over the Internet

B. From the Recovery Console launch terminal and run each command separately [1]

rm -rf /Volumes/Macintosh\ HD\ -\ Data/Previous\ System/private/var/folders/*/*/C/com.apple.mdworker.bundle

rm -rf /Volumes/Macintosh\ HD\ -\ Data/Previous\ System/private/var/folders/*/*/C/com.apple.metadata.mdworker

You may be asked for a password. That would be your computer logon password and you WILL NOT see the characters as you type them. Just hit ‘enter’ after you type the password.

This process may take a long time, so be patient.

C. Reboot your computer and log back in as you would normally

OR

A. Log into your computer normally and launch Terminal. Once the Terminal window opens type in the following two commands, one at a time (you may cut and paste the commands):

find /Volumes/Macintosh\ HD\ -\ Data/Previous\ System/private/var/folders/*/*/C/com.apple.mdworker.bundle -mindepth 1 -delete

find /Volumes/Macintosh\ HD\ -\ Data/Previous\ System/private/var/folders/*/*/C/com.apple.metadata.mdworker -mindepth 1 -delete

This process may take a long time, so be patient.

B. Reboot your computer and log back in as you would normally

For either process, once this is done, go back into Terminal and run the following cmd:

To install Catalina:

sudo jamf policy -trigger install-install-macos-catalina

To install Big Sur:

sudo jamf policy -trigger install-install-macos-big-sur

To install Monterey:

sudo jamf policy -trigger install-install-macos-monterey

This will place the installer in your Applications folder and you can run it at will.