Comment 7 for bug 1649725

Looking into the PY8 log files that you sent in your PY8_parallelization tarball, I see the following:

"""
 PYTHIA Abort from Pythia::Pythia: unmatched version numbers : in code 8.219 but in XML 8.205

Start generating events
 PYTHIA Error in Settings::flag: unknown key JetMatching:doVeto

Inclusive cross section: 0.00000000e+00 +- 0.00000000e+00 mb
"""

So there seems to be some mangling between different version of Pythia8 installed on your system.

If you are not running in multi-core but on a cluster instead, then the origin of this problem is that the XML read by Pythia8 at run time will be read on the worker node which has an older version of PY8 installed.
There is not workaround implemented yet, and we have ideas on how to solve that in partnership with PY8 authors, and we will hopefully have this issue fixed in the next releases.
Therefore please confirm that you are attempting to run PY8 in parallel on a cluster and not in multicore.
I assign Stefan P. to this issue, since we already discussed it with him and I want him to be aware of this thread.