What is the OS upgrade helper tool?
Can I download it manually from somewhere / somehow?
https://support.apple.com/en-us/HT201475 mentions:
"You may be asked to sign in with an administrator name and password to install a helper tool, then click Add Helper to continue."
I'm getting the following error:
Error: -[OSISClient prepareOSInstaller:error:]_block_invoke, Couldn’t communicate with a helper application.
MacBook Pro (Retina, 15-inch, Late 2013), OS X Mavericks (10.9.5), 2.6GHz IntelCorei7; 8GB1600MHzDDR3;