ceph-dencoder decode PGMap failed

[<simplemaomao@xxxxxxx>]

Hi cephers
I want to decode pgmap from leveldb，follow the steps below
1.stop monitor
2.ceph-kvstore-tool leveldb /var/lib/ceph/mon/ceph-lab1/store.db get pgmap first_committed out /tmp/pgmap_first_committed
3.ceph-dencoder import /tmp/pgmap_first_committed type PGMap decode dump_json
the last step return error "error: buffer::malformed_input: void PGMap::decode(ceph::buffer::list::iterator&) unknown encoding version > 6"
ceph version 10.2.10 (5dc1e4c05cb68dbf62ae6fce3f0700e4654fdbbe)
Thanks
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