Apple - MongoDB doesnt' work after update to macOS Catalina 10.15

Move your old /data/db folder into a non root folder and do the following:

brew uninstall mongodb
brew tap mongodb/brew

brew install mongodb-community

"brew install mongodb" won't work anymore as the mongodb is removed from the homebrew-core.

check https://github.com/mongodb/homebrew-brew for more info

ref: https://stackoverflow.com/a/57881349/10818622

I updated to Catalina 10.15.2 from 10.14.X and the new security failed to recognize mongo as a trusted developer. Trying to run mongod in terminal triggered a system dialog (popup) refusing to run mongod with no option to override it.

System Preferences > Security & Privacy > General has a section at the bottom for app developer identity settings and also reports any recent related service denials. This is where you will find the coveted Allow Anyway button:

Click that and run mongod in terminal again. You'll get a new security dialog with an Open button. Click it and mongo is back in the trust circle.

For me it works without brew: Go to the folder, where the mongod binary is saved. Right click on it and then say: Open with - Terminal. It will ask you, if you really want to open. Click open. After that you can open it always without any further question dialogs.