Unable to update to macOS Monterey

we need more info to answer this.

is your mac listed below?

if yes, what is your current version of macOS installed on the mac?

how much free space do you have?

you may want to read this informative user tip: How to upgrade to Monterey - User Tips

gajendra113 wrote:

I am unable to upgrade to latest system

If your Mac meets the hardware requirements for Monterey an you have at least 50 GB of free space on your boot drive try the following:

I've had better luck from the Safe Mode because I evidently have some 3rd party software that interferes with the installation so try the following:

#1 - boot into Safe Mode according to Start up your Mac in safe mode - Apple Support.

NOTE: Safe Mode boot can take up to 3-5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

#2 - go to the System/Software Update preference pane and begin the download.

#3 - run the installer from the Safe Mode.

What model and year Mac? WHat is present macOS version?

Not all Macs are compatible with Monterey.

Is Monterey offered in Software Update? If yes, what happens when you try to update?

Do you have enough free disk space?

If upgrading from macOS Sierra or later, your Mac needs 26GB of available storage to upgrade. If upgrading from an earlier release, your Mac needs up to 44GB of available storage.

Also uninstall any antivirus and "cleaning" apps before trying installing again.

Further, you need an Apple disk installed to upgrade to Monterey since the upgrade includes an update to the Mac's firmware. That update looks for an Apple disk and write to the dick to do the firmware update. The install will terminate or freeze if no Apple disk.

Some users have problem with skipping upgrade versions and even not updating to the latest version of Big Sur.