Hi, it is now upstream's bug: https://sourceforge.net/p/ecls/bug/305 after some discussion on the sage-devel mailing-list, it was found that the problem is related to gmp 5.1.3 vs gmp 6.0.0. I also notice that if I force ECL_OPT_SET_GMP_MEMORY_FUNCTIONS to 0 in src/c/main.d, then the crash disappears : it's a workaround. Snark on #debian-science