…and spewing errors into a logfile as a result.

Particularly annoying with ORCA, as it spews into the ORCA output every time it starts or finishes a step.

Easy fix; add to .bashrc:

export OMPI_MCA_btl=^openib

Done.

Seems that the Ubuntu 16.04 version has a few extra flags set in the compilation when compared to the 14.04 version, as I never used to have this.