1.9.0-beta5 has a dual focus. One priority is to fix longstanding multiplayer and networking bugs. The other priority is to refactor the engine and its public API to be more clearly separated from the games, and to allow future development of the engine without breaking game_plugins.
There is a huge list of changes for this release, as one can expect after a 7 month development period.
Do not install over Beta 4 or a release older than that. You will more than likely face strange problems if you do. (Installing over Beta 5 release candidates is OK.) If you want to retain your old Beta 4 installation, just install Beta 5 into a new folder.
During the release candidate phase there were several issues with clients connecting to a server, where other clients sometimes crashed, or the new client was denied access due to a “ghost” player left behind by a client that had previously exited the game via crashing. Even though many reasons for these crashes were found and eliminated, there may still be circumstances where crashes on client joining occur.</noinclude>
Cl_Frame2Received: Unknown delta type 5.
before swapping GL buffers. Intended to be a workaround for ATI driver problems. http://ati.cchtml.com/show_bug.cgi?id=122