"Waiting for another package manager to quit..."
I quite often get the "Waiting for another package manager to quit..." message in Pamac which prevents me from installing anything with Pamac. The thing is that there can't be any other package manager active because I can successfully install packages with PacUI or directly with Pacman while Pamac continues to show the "Waiting for another package manager to quit..." message when I try to install something with Pamac. A reboot solves this problem.