Where and how can I ReDownload the Installer for macOS Monterey?

Trash the old Install Monterey from /Applications and then Shift-boot into safe mode and download a new copy from App Store.

https://support.apple.com/en-us/HT210190

But, as usual, make good backups before any major update!!

Has one attempted the below >>

As late resort, also from Safe Mode -  In Terminal " softwareupdate -l " without quotation marks.

The same procedure re-quotation marks this command "  softwareupdate --fetch-full-installer --full-installer-version 12.0.1 ".

This should download the Full Installer and place a new Application called " Install Monterey " in the Applications folder.

If successful - it will not launch but just sit there.

Do the TM Backup and if wanted, copy the installer to good external drive for future purposes like a bootable installer.

Run the Installer at this point.

Follow the advise @Matti Haveri has suggested.

As late resort, also from Safe Mode -  In Terminal " softwareupdate -l " without quotation marks.

The same procedure re-quotation marks this command "  softwareupdate --fetch-full-installer --full-installer-version 12.0.1 ".

This should download the Full Installer and place a new Application called " Install Monterey " in the Applications folder.

If successful - it will not launch but just sit there.

Do the TM Backup and if wanted, copy the installer to good external drive for future purposes like a bootable installer.

Run the Installer at this point.

open or search for your terminal and paste this line softwareupdate --fetch-full-installer

You have to delete "Install macOS Monterey" from the Applications folder before you try in Safe Mode.

As suggested by previous posting.

There are factors:

1 - Like poor Wifi connection

2 - Slow wifi connection

3 - Too many other people downloading at the same time and Apple Severs are overloaded

4 - Software on the computer interfering with the download process including AntiVirus Software

5 - Running behind a VPN which may increase Packet losses and a incomplete or corrupted download

6 - If via wifi too many Other devices using the wifi at the same time reducing the Bandwidth to your computer. 

7 - Best Results are via Ethernet Cable to Router

Trash the installer again and try while in Safe mode.

How to use safe mode on your Mac - Apple Support

Tried downloading and launching several times from safe mode. Both through App Store and from command line, as above. I still got "An error occurred loading the update." I have 500GB free on disk, so doesn't seem like space.

Updating from Big Sur 11.6.2 - MacBook Pro 13-inch 2019

After rebooting (always in safe mode), I usually get a different error using the same installer - "Installation connect be processed because the installer is damaged. <br> Redownload the installer and try again." Makes me wonder if the initial fail alters the install package.

Next time I'm going to make a copy of this 12GB installer package (if I try again) because it's pretty annoying to download each time, or see if I can find a zipped version somewhere w an md5 so I can verify the download once and keep a clean copy.

Anyone knows what to do, if the error persists even after re-downloading?

Just tried safe mode. Tried both re-installing the package that was already downloaded, but also re-downloading the package in safe mode... same error indicating that the package is damaged.

Thanks, dialabrain, for replying. Before I try that (it does take some time), could you please explain the difference between deleting the package before and after entering Safe Mode?

:) As long as you delete the installer before you try in Safe Mode, it matters not.

That's what I thought :-)

As I am still unable to update... any other ideas to try? :-)

Would it make sense to put the image onto a bootable USB drive and try installing from that media?

What model/year Mac do you have?

2017 iMac. All stock except for some added (OEM) RAM.