Dear @asmecher , dear @felixhelix
as far as I can see, the tar executable is not used anymore by the latest version of the PLN Plugin, isn’t it?!
See my recent findings on paths for the PLN Plugin: PKP PLN Plugin ask for Archive_Tar PHP extension - #49 by klausru
Make sure PEAR is in open_basedir AND include_path (with first in order)
All the best
Klaus