MacOS 10.15 Catalina fails to burn bootable cdroms from ISOs

Not likely to impact most people, but occasionally I use an external USB dvd burner to make bootable disks for installing various OSes on older computers.

Previously before Catalina I would right click an ISO and select “Burn Image to…’ and this would work as it has for the past several MacOS releases. Now though when I click this option the menu disappears and nothing happens. A tip here suggested to double click this iso to mount it, and then right click the mounted disk and select “Burn Image’. While this does work to burn to a blank cdrom, the disk is not bootable, it appears to only copy the files to the cdrom and not burn it as a bootable disk, even if the iso is from a bootable disk.

Reading through the above post on the Apple site, this sounds like a bug in Catalina and has been logged.

MongoDB on MacOS Catalina 10.15: “exception in initAndListen: 29 Data directory /data/db not found”

By default, MongoDB usually stores it’s data files when running on MacOS under /data/db. After upgrading to Catalina 10.15, when starting MongoDB I get this error:

STORAGE  [initandlisten] exception in initAndListen: 29 Data directory /data/db not found., terminating

According to this question and answer here, Catalina no longer allows apps to read or write to non-standard folders beneath / so you need to move the data files elsewhere. After my upgrade, the files were moved to a ‘Relocated Items/Security’ folder. Moving them into my user dir and then starting up with the suggested:

mongod --dbpath ~/data/db

fixes the issue.