Hello,
What region are you playing in, and what physical region of the world are you located in?
Sad to say, but the vast majority of these cases are caused by connection errors caused by a region mismatch due to poor local/server connections. A VPN is the best way to handle this. It's worth noting that a single VPN won't always route you around the problem. We recommend trying a wide variety of VPNs and multiple servers on multiple VPNs to see if they route you around the problem in question, since it's difficult if not impossible to determine where the problem is.

Alternatively, it's also possible your install was corrupted. If that's the case, reinstalling the client or installing an older version of the client can fix the problem.

Hello, basically I tried everything to fix also VPN doesn`t work too. I live in UK, London. Btw I can play the game with older mini client for the moment but It is not good. I started thinking there must be missing file in the computer that`s why It doesn`t even open.

And are you playing in the UK region as well? As I said, a lot of these issues are caused when players are physically distant from their server location.
You said you tried a VPN. Have you tried multiple VPNs? Have you tried multiple servers on the the VPNs to see if they route you around the problem?
If you're able to play on an older version of the miniclient, it might have just been a problem with the install. Have you tried reinstalling the client?

I tried everything, delete install again also VPN different ways. The client is not even opening that`s kind a problem.

OK, at this point we recommend putting in a CS ticket so they can investigate the issue for you. Here is the link:

This was never an issue before... why it's suddenly an issue after last night's maintenance is anyone's guess.

Release notes/changelog ~ would be nice. But I guess the convenient workaround for Oasis is to recommend VPN or another version install? Very odd...