Very recently, my League suddenly stopped working. At first, when I logged in the client wouldn't load (even though a few hours earlier I played a few games) and I was asked to Exit. When I launched it again and clicked login, the launcher got stuck at "Authenticating" for a few minutes before a message appeared saying that an "unexpected error" appeared. I then closed it once again and tried to reopen it. This time, however, the League logo appeared in the dock, bounced a few times and just stayed there without the launcher opening. In order to close it I had to "Force quit" it.
After a few tries, the same thing kept happening so I decided to uninstall it and install it again. This time, when I opened it everything worked fine and I played a few games. Later in the day I reopened it and the same thing happened as last time (client not loading, stuck at "Authenticating" and then game not opening at all). Today I decided to reinstall it once again and the same thing happened. The first time I open it everything works fine but after that the problems appear again.
I tried using the Hextech Repair Tool but it didn't do anything and I have submitted a ticket to Riot support (currently waiting for an answer) but I thought that if I posted my problem here the issue could be resolved faster. I am running macOS High Sierra version 10.13.1