ArenaNet is postponing this week’s second planned beta event for Guild Wars 2's World vs. World restructuring after continued issues. The first beta in September ended after just a couple of hours, and while the team explained why the test had to be scrapped, they were hopeful for the rescheduled date this week. However, that's going to have to wait.
The issues that hampered the test on September 24th are still at the core of what's going on and causing this delay. The update last month identified 10 issues they had to fix before carefully running further tests, but another issue came up that just won't let them hold the beta now.
"While the code that manages map capacity is used game wide, player counts for WvW are more complicated than other maps because there is a necessary limit to the number of players per team to help maintain competitive integrity. The counting is handled in two places: (1) when a player connects and joins the WvW map, and (2) it’s updated periodically based on a connected player’s HomeShard. The problem is that players are connecting to the map and initially being counted using their World Restructuring team, but the periodic update is looking at their HomeShard. This causes all sorts of interesting side effects."
The good news is the team knows what to do to fix this issue but the scale of it, with the code (much of it legacy code) affecting the entire game, just means they need enough time to do it slowly and carefully).
The planned WvW restructuring is something that will change the entire system, and the current block is an issue that requires a change to code affecting the entire game. It makes sense that they would tread carefully, and canceling the beta event ahead of time seems like a wise move.
For the full update on why the event is postponed, including many technical details, see this post on the Guild Wars 2 site.