I have a mac, so I'm not sure what the solution on a PC would be, but seeing how it resolved the issue, I think it could work also.
I kept getting the error message within the launcher that would make it hang up on "Connecting to patch server" then would get stuck on "An update error has occurred." and then would keep retrying over and over again before the launcher would kill itself.
After doing a shiz ton of research I noticed something that was wrong in the naming of the lotroclient.
On a Mac:
Go to the Applications Folder
Right click "The Lord of the Rings Online™" icon and select "Show Package Contents"
Open the "Contents" folder
Then open "Resources"
There you will see another "The Lord of the Rings Online™" icon. Right click this one and select "Get Info"
In this window you will see all kinds of information about the .app
Find "Name & Extention:" and see if the name of this .app is "lotroclient.app" or "The Lord of the Rings Online™.app" If it is "The Lord of the Rings Online™.app" CHANGE it to "lotroclient.app" and then try to re-run the game. This fixed the problem for me and the game worked fine.
In short, renaming the .app to what it is supposed to be named fixed the issue. Why it got renamed, I'm not for sure. haha
I'm not for sure how to fix the issue on PC side. But if it has to do with renaming something, I'm sure you all will figure it out. :P