When using pkgadd(1M) during installation, if you encounter the following error message:
#Waiting for up to <300> seconds for package administration commands to become available (another user is administering packages on zone <XXX>)
An interruption of the pkgadd(1M) process can leave an outstanding packaging lock file, which blocks further use of the pkgadd (1M) command. Before attempting another installation, remove the packaging lock file.