"Scrivener/Scapple can't be updated" error
If when trying to update Scrivener or Scapple you receive the error that the application "can't be updated when it's running from a read-only volume like a disk image or an optical drive", this can mean one of two things. First, you may be running the application from a DMG ("Disk IMaGe") file, so the application cannot be overwritten with the new version, or you do not have the necessary permissions to install software on your Mac.
A disk image is essentially a virtual disk, just like how most software used to come on a physical disk that you would insert into your CD drive. When you download Scrivener or Scapple, the files that download are entitled "Scrivener.dmg" and "Scapple.dmg", respectively. It is important to understand that these disk images are intended only for installation - once you have installed Scrivener or Scapple, you can safely discard its .dmg file (for full installation instructions, see Installing Scrivener for macOS.) Thus, if you are encountering the above error message, it's possible you have not installed the software properly (you may, for instance, have dragged the application from off the disk image's pop-up window and directly to the Dock, missing the important intermediary step of first placing it in the Applications folder).
To resolve the issue, it is recommended that you first uninstall the application (to do this, drag Scrivener or Scapple from your Applications folder to the Trash in the Dock, then empty the Trash) and then follow the instructions to reinstall the software. In newer versions of Scrivener and Scapple, it will attempt to detect when you are running it from an improper location, and give you options for rectifying the situation automatically or to cancel and install by hand.
If this does not resolve the issue and you have definitely installed the application properly, check that you have the necessary permissions to install software on your machine (you must have administrator permissions to install software on macOS). If you still have problems, please contact our technical support team.