Monterey OS installation

When are you getting the message?

When you start download?

When You try to run the installer?

What is exact wording of the message?

You do have a MacBook Pro

Early 2015 and later

If you are downloading from System Preferences>Software update?

If so try going to App Store and search for macOS Monterey and try downloading from there.

Further try booting to Safe Mode and downloading and installing

How to use safe mode on your Mac - Apple Support

Some users have had problems if Big Sur is not fully updated first. Is your Big Sur fully updated?

Welcome to Apple Support Communities.

Install macOS Monterey like any other macOS upgrade: How to upgrade to macOS Monterey - Apple Support.

Are you seeing an error and cannot proceed?

Jack

This maybe an indication of a failed download and the Application is still present in the Applications folder, If it exist - Drag and Drop to Trash and empty the Trash.

That or the computer does not have the Empty Space Requirements  >> 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. 

Or worse still

Point # 1A - There are reports appearing on the ASC Forums regarding failed installation of Monterey on older Qualifying Apple Computers. In most cases this is related to having a NON Apple Original internal drive ?  

The EFI Boot ROM included in Monterey is verifying for Original Apple Drive and if not found , may Balk or fail to upgrade to Monterey. 

Reports indicate the EFI BOOT ROM is Required to Flash the Computer and is a  requirement for a Successful Monterey Installation.

Note that the installation will take a long, long time since the volume and to first be decrypted and then encrypted.

monterey downloads then gives me a null message when downloading

monterey downloads then gives me a null message when installing