This version is fully compatible with all previous 1.8 versions, but it is still highly recommend to update to 1.8.8 as soon as possible for both players and servers.
Notable bugs fixed:
Server may not start in some environments
Potential server crashing exploit
Client crashing exploit
Lag exploit with banners
Please make sure that you are in the correct server mode (online mode/offline mode) when you start the 1.8.8 server for the first time, because profiles are not compatible between these two server modes.