If pacemakerd needs to respawn a failed subdaemon, and the pacemaker software has been updated since pacemakerd started, it will start a newer version of the subdaemon than itself (and likely other subdaemons).

Possible solutions:

• Do an initial handshake that includes the Pacemaker version and exit fatally (or do a full restart of Pacemaker) if mismatched.
• At pacemakerd startup, check subdaemon binaries in some fashion (hash or file characteristics) and exit fatally (or restart) if mismatched when respawn is needed.