Have latest Etcher, using Mac to make ubuntu boot stick or card. Have tried both and with different .iso downlad files. Can’t burn to target as always get Flash Failed, 1 Failed target, EACCES: PERMISSION DENIED, open ‘dev/rdisk5’ . Permissions for target = “custom” and cannot be changed – I am for sure Administrator.
check in System Preferences > Security & Privacy > Privacy… scroll down the list of parameters on the left to “Full Disk Access” and then add BalenaEtcher.app (by finding the app in the Applications folder). Be sure to select the checkbox to the left of the app name.
I have BigSur.
I also added Disk Utility.app so I could make disks.
as @peter40b mentioned, you may have to double check the security settings on your macOS. I’m running macOS as well and have no problems using etcher to flash a bootable usb stick or card.
You may have to enable the access for
removable volumes. I’ve added a screenshot from my development host:
Let us know if this helps.