I can't open quickbooks 2015 desktop version on my new iMac which runs Monterey ios 12.2.1

QBD 2015 is outdated and doesn't support Monterey. Purchase QBD 2022 to upgrade your files for $275 or less, or QBD 2023 next month for $550.

Welcome to the QuickBooks Community, cbatllc_dave.

The 2015 version has been retired and may not work especially if there are new updates on Mac computers. Therefore, I agree with Fiat Lux - Asia about upgrading to the latest version. Check out the features of QuickBooks Mac Plus 2022.

To upgrade your file after installing the new version:

1. Open your new version of QuickBooks Mac.
2. Select Open or Restore Company and find your backup file (.QBB) or your DMG file.
3. Browse your company file and then Open.
4. Sign in to your company file as an admin user.
5. Select Update Now to start the upgrade.

You can always go back to this thread if you have any other questions in mind. Take care and have a good one!