That error up there has been causing me some head scratching. I couldn’t figure out what the problem was, and it causes issues with different parts of WordPress. I was seeing it on the Dashboard but it stops things like upgrades and plugins installing. I tried different solutions, adding .htaccess files etc etc. None of it looked that convincing, and none of it worked. Then one evening, this evening in fact, as I uploaded the newest version of WordPress (3.2) because the automatic update wouldn’t work it occured to me that I hadn’t tried poking the firewall.
It was the bloody firewall! Blocking all outgoing connections. Although this is good for security its not good for WordPress. So if you are seeing this error and have tried everything else. Take a look at your firewall. I wish I had weeks ago.
Is it trying to make an outside connection via the client (i.e. Javascript through the browser) or are you hosting your WP internally? I’m getting this same error too and it has me stumped and it doesn’t matter where I’m accessing it from (home, work, iphone, etc…).
It’s the firewall on server that your WordPress site is hosted on that could be causing you the problem. If you are using a hosting company ask them if their firewall allows outgoing connections. If it is your own server you need to look into the firewall configuration.
As it is the sever, you will see it whatever method you are using to access the site.