can't open database after upgrading to Mac OS Monterey 12.0.1

I'm guessing you have a M1 mac. Have you downloaded Rosetta2 yet? You should be able to find it in the App Store.

If you still have issues, then you should contact Ninox support.

Ninox is a universal app, so it doesn't needs Rosetta.

I am too have an M1 Mac. I don't have problems with Ninox app and macOS Monterey.

From Apple:

- Application (Intel) means the app supports only Intel processors and needs Rosetta to work on any Mac with Apple silicon.
- Application (Universal) means the app supports both Apple silicon and Intel processors, and uses Apple silicon by default.