Due to the update of the permission system and the default system shell from bash to zsh in macOS Catalina 10.15, it was found that starting MongoDB from the command line was not working as before. After running the command, an error message was directly reported: “Developer cannot be verified”, as shown in the figure below: Solution: Open System Preferences and go to Security & Privacy, click on Allow Anyway on the right side of the red rectangle at the bottom to resolve the issue.