Thanks for tip. I did Pkg.rm("IJulia") followed by Pkg.add("IJulia"), and that allowed me to start up IJulia with the correct kernel. I still do have problems running a notebook that used to work under Julia v. 0.6.2, so I tried to subsequently do Pkg.build("IJulia") – seemed to work, but there was an error message referring to kernel-spec or something; still the notebook started (but couldn’t execute as before; see separate thread).