Redis issue with 'mset' ?

[xme]

My Karton was stable but for a few days, I see this:

Dec 22 14:05:16 malawi karton-system[702206]: Traceback (most recent call last):
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/bin/karton-system", line 8, in <module>
Dec 22 14:05:16 malawi karton-system[702206]:     sys.exit(SystemService.main())
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/karton/core/utils.py", line 122, in newfunc
Dec 22 14:05:16 malawi karton-system[702206]:     return self.func(owner, *args, **kwargs)
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/karton/system/system.py", line 345, in main
Dec 22 14:05:16 malawi karton-system[702206]:     service.loop()
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/karton/system/system.py", line 255, in loop
Dec 22 14:05:16 malawi karton-system[702206]:     self.process_routing()
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/karton/system/system.py", line 246, in process_routing
Dec 22 14:05:16 malawi karton-system[702206]:     self.handle_operations(bodies)
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/karton/system/system.py", line 223, in handle_operations
Dec 22 14:05:16 malawi karton-system[702206]:     self.backend.register_tasks(tasks)
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/karton/core/backend.py", line 310, in register_tasks
Dec 22 14:05:16 malawi karton-system[702206]:     self.redis.mset(taskmap)
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/redis/commands/core.py", line 1906, in mset
Dec 22 14:05:16 malawi karton-system[702206]:     return self.execute_command("MSET", *items)
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/redis/client.py", line 1238, in execute_command
Dec 22 14:05:16 malawi karton-system[702206]:     return conn.retry.call_with_retry(
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/redis/retry.py", line 46, in call_with_retry
Dec 22 14:05:16 malawi karton-system[702206]:     return do()
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/redis/client.py", line 1239, in <lambda>
Dec 22 14:05:16 malawi karton-system[702206]:     lambda: self._send_command_parse_response(
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/redis/client.py", line 1215, in _send_command_parse_response
Dec 22 14:05:16 malawi karton-system[702206]:     return self.parse_response(conn, command_name, **options)
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/redis/client.py", line 1254, in parse_response
Dec 22 14:05:16 malawi karton-system[702206]:     response = connection.read_response()
Dec 22 14:05:16 malawi karton-system[702206]:   File "/usr/local/lib/python3.8/dist-packages/redis/connection.py", line 839, in read_response
Dec 22 14:05:16 malawi karton-system[702206]:     raise response
Dec 22 14:05:16 malawi karton-system[702206]: redis.exceptions.ResponseError: wrong number of arguments for 'mset' command

It seems to be related to a server upgrade... Any idea?