Upon launch Minecraft tries to write to the application folder. Of course, as per standard security practices, the application folder is not writable by normal users. Minecraft then displays the erroneous error message that it’s being run from a DMG volume.
See earlier reports that have been incorrectly closed
This bug has been active for at least 2 years.
Correct behaviour is one of:
Test for write access and don’t assume that the application can write to the application directory. Don’t do download if not writable.
Test for write access and don’t assume that the application can write to the application directory. Request elevated privileges before trying to write to application directory. Only write if elevated privileges are granted.
Use an appropriate writable directory NOT. THE APPLICATION DIRECTORY
Linked issues
Comments 4
Looking at the related issues, this bug has been around for at least 5 years.
Given a basic work around is to check for write access and gracefully skip downloads, a fairly trivial process, there is really no reason this bug has not been at least worked around.
Setting categories for a bug should not be something that a customer should be expected to do when they report a bug. That should be part of your internal triage process. Please update it if your internal process requires it.
Use the MCL category on bugs.mojang.com