In the firmware download there are release notes, with all this information. Even if your specific situation is not listed, it is still a good idea to upgrade to the most current.
Out of nowhere one of the member interfaces in the Portchannel is trasitioning from "Forwarding to Blocking State" this has happened twice within a span of 2 weeks.  This shouldn't have happened because STP would ignore the physical interfaces and instead treat the port channel interface as one link.   The portchannel is between a cisco 4900M and PowerConnect M6220 .   Are there any known bugs relating to LACP/port channeling in code 3.1.3.9 ?
Any known bugs relating to Portchanneling using LACP on M6220 running code 
3.1.3.9