GW2 has been updated. Please exit and relaunch it. (Code=164:5:1:318:101).

[Justin Time.7054]

I get to the characters page, then hit "Play" and It displays this error message since hours ago.
I tried to relaunch it many times, during the first times it also displayed an error connection to the server, then it disappeared.
What can I do?

Edited March 19 by Justin Time.7054

[Healix.5819]

This is what they use to check if there's a patch (the first number is the build):

http://assetcdn.101.arenanetworks.com/latest64/101

The current build is 159951. I'm assuming you're seeing something different, so either you or your ISP is caching websites, or the server failed to update.

First, simply reset your DNS. Press WindowsKey+R, open:

ipconfig /flushdns

Try launching. If it still fails, you can try changing DNS providers:

https://developers.google.com/speed/public-dns/docs/using

If it still fails, you'll need to manually select a different server. Search the start menu for cmd, right click it and run as administrator. The title of the command prompt window should begin with Administrator, showing it's being run as an admin (required). Copy the following line and right click the command window to paste it, then press enter:

echo.99.86.37.92 assetcdn.101.arenanetworks.com>%windir%\system32\drivers\etc\hosts

Now you should be able to patch. Eventually the IP will change and the launcher will fail to connect, so run this command to undo the previous:

echo.>%windir%\system32\drivers\etc\hosts

Edited March 19 by Healix.5819

[Stelawrat.6589]

6 hours ago, Justin Time.7054 said:

I get to the characters page, then hit "Play" and It displays this error message since hours ago.
I tried to relaunch it many times, during the first times it also displayed an error connection to the server, then it disappeared.
What can I do?

I've never used ArcDPS, but just in case you are, then this might apply to your situation, if none of Healix's suggestions work for you. Arena has a dedicated page with other options here: Repairing the Game Client – Guild Wars 2 Support 

Removing ArcDPS#

After Guild Wars 2 updates, ArcDPS may start crashing the game. Remove ArcDPS until a new ArcDPS update is released.

1. Open the installation folder for Guild Wars 2. It’s usually something like “C:\Program Files (x86)\Guild Wars 2”.
2. Open the “bin64” folder.
3. Delete d3d11.dll. Alternatively, disable ArcDPS by renaming it to “d3d11.dll.bak”. Undo the name change to enable it again.

[Bun.6473]

Just encountered the same thing. No addons whatsoever, worked half a day ago. Rebooted everything, repaired the game - no joy.

After repairing it starts giving me the "The game client lost its connection to the server" error (Code=7:11:3:202:101)

Submitted a ticket - we'll see. Internet works like a charm, no hindrances. Friend logged in on another PC - works too. Guess its either client or me provider being funny all of a sudden... 😕

[Justin Time.7054]

I waited one day without further trying to open the game.
Just now I tried again, it updated correctly and the login was successful.
I hope it will happen the very same to Bun too.
Thank you Healix and Stelawrat for useful information.
I will save suggestions, just in case 🙂