After patch I get "Unable to validate game version"..

[Ualaa]

I've had a similar error in the past, when I had patched without first breaking my symbolic links.
Unfortunately, both times I had this, the only solution that worked was a reinstall.

If you go that route, back up your WTF folder.
So you'll at least have all your settings and such.

If your addons are up to date, it wouldn't hurt to backup the Interface folder too.

It is the game files which are the problem.
One of the warcraft games has patched successfully, but the others have not.
And because the registry now thinks everything is up to date the others will not patch.
But the game cannot run the unpatched version.

If you have one folder which will run, you could try deleting the others.
At least the Data and Cache folders, and wow/launcher executables.
Then copying from the working folder.
If you don't have any folders that will run, the reinstall is probably your only option.

As mentioned in the previous post, the repair tool is a decent option to try first.
Before a reinstall.
Also a post on the technical support forums can sometimes help.

[Xorn]

As far as I know that is a pretty common issue with .3 and since it doesnt affect your gameplay at all I would simply ignore it - I get it almost every day and completely random - sometimes my main won't login at first because of this issue and somethings its toon no. 2 or whatever.

I guess this is going to be fixed sometime in the future since it's not really a problem - at least for me.