The Line6 updater utility didn't start on my Mac.
I found that this was due to my File System with case sensitivity.
Command line startup displayed
...
QQmlApplicationEngine failed to load component
file://applications/Line6/Line 6 Updater.app/Contents/Resources/qmlsource/main.qml
So "/applications" did not exist on my Mac it was "/Applications"
Dirty workaround:
sudo ln -s /Applications /applications
This allows Application startup.
Afterwards the link can be removed by
sudo unlink /applications
I hope that Bug will be fixed soon by Line6 Developers