Could not sign in to iMessage.

same here, iphone and ipad on the same network works fine, Messages app on ML 10.8.2 keeps not logging-in.

Same here. I can login to iCloud, App Store etc. But cannot login to iMessage on iOS or OS X. Have tried every possible solution online. Maybe Apple servers are down due to influx of iOS updates?

same here, upgraded to ML today and haven't been able to log in to imessage at all.

Open Keychain and search "iMessage" just delete all the items. Then try signing in again. I think it may be a problem for those who were using the Messages beta.

just tried, still the same error.

this is what system.log says:

Sep 21 23:47:31 Micheles-MacBook-Pro.local Messages[14493]: [Warning] Empty account query with service: iMessage

Try quitting Messages, and killing "imagent" with Activity Monitor. Took me a few tries but mines working now.

killed the process, saw it changing pid, Messages.app still doesn't log in.. what the ####!

So, here's a recap of what I've tried so far:

Deleted:

~/Library/Preferences/com.apple.imagent

~/Library/Preferences/com.apple.imservice.*

~/Library/Preferences/com.apple.imessage.bag.plist

iMessage entries on KeyChain

Killed imagent

Turned on WiFi and updated "Set time zone automatically" (read somewhere someone resolved with this on Messages beta)

My DNS servers are the Google's ones: 8.8.8.8 8.8.4.4

and... Messages/Facetime doesn't login, it responds: The server encountered an error processing registration. Please try again later.

(just so you know, iMessage on my iphone and ipad on the same network are working flawlessly)

Hi,

We are of course saying this on iPhone 5 Friday with expected sales that may top 8 million units.

My iPhone is having trouble just sending messages and it was updated two days ago.

Of course it may not all be down to the Servers being busy but it will be a good part of it.

11:59 PM Friday; September 21, 2012

Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"

 iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.2)
 G4/1GhzDual MDD (Leopard 10.5.8)
 MacBookPro 2Gb (Snow Leopard 10.6.8)
 Mac OS X (10.6.8),
 Couple of iPhones and and iPad
"Limit the Logs to the Bits above Binary Images."  No, Seriously

I don't think it's due to servers congestion or something like that, mine stopped working the very moment I rebooted with 10.8.2 installed. (btw, still not working)

I think everyone who has issues should contact +1-800-694-7466 and report the case with Apple. Or call your Apple tech support number in your country. When the call centre cannot fix it, they send it to engineering department. The more people call and report the issue, the more they would look into it for a fix or might treat as a single account issue.

So everyone call and report please.

got it working, clean up your /etc/hosts