Back up MainStage
Before you update MainStage, back up your current copy of the MainStage application and your existing concerts.
Backing up the MainStage app allows you to move your concerts to another Mac so you can continue to use these concerts in the earlier version of the app if there's an issue after updating.
Back up the MainStage app
Create a new folder in the Applications folder.
Name the folder with the name and version of the application (for example, “MainStage 3.6”). To check the version of MainStage you have, open the application, then choose About MainStage from the MainStage menu.
Select the MainStage application in the Applications folder, then choose File > Compress “MainStage.” It takes a few minutes to compress.
Move the resulting “MainStage.zip” file into the folder you created in step 1.
Move the folder containing the ZIP file to a backup drive.
Back up your MainStage concerts
To back up your MainStage concerts, you can use a system-wide backup solution like Time Machine or you can simply copy your concerts to a dedicated backup drive.
By default, your concert files are in the MainStage folder of your Music folder.