Comment (by Roland Haas):

Fixed in git hash c049b72e "CarpetIOHDF5: only store active region for grid functions in sliced output" of carpet. I could reproduce the issue (using 12 MPI ranks though I don’t know if 12 is critical or just anyt-number-larger-than-1) with Gwyneth’s parfile in ET_2016_11 of Carpet and it is first gone in ET_2020_11 (or any commit starting with c049b72e).

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2018/assertion-all-stride-otherstride-failed