Firmware update needed to install Monterey

The OP is using the original drive:

" The internal drive is the original 500GB Apple drive it came with, so that isn't the issue."

the Beast of Middlesex County wrote:

I have a late-2013 Mac Pro that I am trying to upgrade from Big Sur 11.6.2 to Monterey 12.1. The installer downloads fine, but when I run it it tells me that it cannot install the OS because the EFI firmware is out of date.

I checked and the machine is running version 132.0.0.0.0. A quick check of the Internet tells me that this is seriously out of date. The internal drive is the original 500GB Apple drive it came with, so that isn't the issue.

I have no idea why the firmware was never updated when the OS was updated in the past. The only manual installer I could find is for Mavericks.

Is there ANY way of updating the firmware short of backdating the entire OS?

Reinstall the Apple OEM NVMe / PCIe SSD— upgrade that drive to get the EFI update in place. Then reinstall your third party drive and continue with your upgrade macOS.

The EFI /Firmware part of the Monterey pkg is verifying for OEM Apple Drives and fails to upgrade. The EFI boot ROM is required to Flash the board and is required to successfully install Monterey.

the Beast of Middlesex County wrote:

I have a late-2013 Mac Pro

For your Desktop computer you can verify from the >About this Mac

How to upgrade to macOS Monterey

https://support.apple.com/en-us/HT212735

iMac late 2015 and later

iMac Pro 2017 and later

MacBook Air early 2015 and later

MacBook Pro early 2015 and later

Mac Pro late 2013 and later

Mac mini late 2014 and later

MacBook early 2016 and later

>(Option key) System Information>Hardware>Storage> you can verify OEM

Backup your data/files. Download the various installers for older macOS version which you can get here:]

How to get old versions of macOS - Apple Support

Make bootable USB installer using:]

Apple’s instructions

How to create a bootable installer for macOS

and boot from then and install that macOS version. Repeat until you at Big Sur then upgrade to Monterey and finally migrate you data /file from backup

The only standalone firmware I could find is:

https://support.apple.com/kb/DL1714?locale=en_US

Mac Pro EFI Firmware Update 2.0

The following lists some firmware version and what macOS version updated them.

https://blog.greggant.com/posts/2019/05/07/the-definitive-mac-pro-2013-trashcan-guide.html#tfirmware

However, not it does not included the update for Monterey since the Monterey update changed the description and numbering system. Now the About this Mac>System Reports included this for my Monterey trash can

 System Firmware Version: 429.60.3.0.0

 OS Loader Version: 540.60.2~89

which replaces EFI firmware version.

If