I did a freebsd-update to RC2 yesterday evening. On rebooting with the new kernel, my zfs mounts were not present. In single user mode, the zfs command was core dumping. Fix was to copy /boot/kernel.old to /boot/kernel Backtrace is not super useful I think: lldb) bt * thread #1, name = 'zfs', stop reason = signal SIGABRT * frame #0: 0x000000080137884a libc.so.7`__sys_thr_kill + 10 frame #1: 0x0000000801378814 libc.so.7`raise + 52 frame #2: 0x0000000801378789 libc.so.7`abort + 73 frame #3: 0x0000000801082913 libzfs.so.2`zfs_standard_error_fmt + 1603 frame #4: 0x00000008010822c5 libzfs.so.2`zfs_standard_error + 21 frame #5: 0x0000000801091da2 libzfs.so.2`zfs_open + 290 frame #6: 0x00000008010838a5 libzfs.so.2`zfs_path_to_zhandle + 85 frame #7: 0x0000000000410005 zfs`___lldb_unnamed_symbol76$$zfs + 437 frame #8: 0x000000000040811b zfs`___lldb_unnamed_symbol18$$zfs + 635 frame #9: 0x00000000004059c2 zfs`___lldb_unnamed_symbol5$$zfs + 834 frame #10: 0x000000000040552f zfs`___lldb_unnamed_symbol1$$zfs + 383 Mark