UPDATE: The Lord of the Rings team has updated the status of the launch of the Mordor expansion. It was originally set for release on July 31st but a persistent issue cropped up to stop the deployment. That issue has been tracked down and all systems are go for the Mordor launch on Wednesday, August 2nd.
Read more on the LOTRO site.
ORIGINAL STORY:
The Lord of the Rings Online site has been updated with the sad news that the launch of the Mordor expansion will not happen on Monday, July 31st as originally planned. The team discovered an issue with the build that made monsters and NPCs move incorrectly. While sad for those looking forward to Mordor, the wording on the expansion does give an out by saying it will be delivered on or before August 31st. The target was July 31st, but there is still plenty of time to head through the Black Gate.
We are as excited as many of you to get into Mordor, but we have some unfortunate news: we have to adjust the release date. While preparing over the weekend to release the expansion on Monday, we discovered an issue in the build that impacted the ability of monsters and NPCs to move around correctly. This problem was specifically identified in older content. While correcting this issue is not a problem, the process to correct it takes too long to be able to release Mordor on Monday. So, we have to adjust the release date. We will have more info on the release date soon. We will know a lot more in the next 24 hours or so, and will pass along the info as soon as we can.
Link: Lord of the Rings Online forum