"An error occurred during activation. Try again." Why can I not sign into imessage?

Question

"An error occurred during activation. Try again." Why can I not sign into Imessage?

Answer 1

Hi,
You stated earlier that you had already deleted the "madrid" .plist with no effect.
Can I check you did this with the app closed down or at least restarted the app straight afterwards ?
If you did that close the app if open and access the ~/Library/Preferences  folder again.
This time delete com.apple.imessage.bag.plist 
This item stores the Apple server used for your Login to the iMessages server and contains a date/time reference.
Restarting the app after deleting this file will make it reconnect with the iMessages servers in a fresh manner which my solve things.
It may sort out any date/time issues with the stored date.
Messages is one of the app that Apple have "Sandboxed".
This means that some of it's operations are held away from other apps to prevent one app bringing down several others.
This is turn means that the route or path used by the app to Read and Write to the various .plists is different to the direct placing in ~/Library/Preferences.
The Path is ~/Library/Containers/com.apple.iChat/Data/Library/Preferences
Mostly the items in here are then Aliases that point to the actual originals in ~/Library/Preferences.  However there are exceptions.
You can copy and paste the Path above in to the Finder > Go Menu > Go to Folder dialogue box to access this folder.
Once there use the Finder's View Menu > Show Path Bar.
This adds a collection of folders across the bottom of the Finder window.
Right click on the Preferences folder at the right hand list of the Path.
Chose the Get Info option.
In the Info panel scroll to the Bottom.
Your Shortname should appear (with (Me) as well) and you should have Read and Write Permissions
If you highlight this and then use the Cogwheel type iCon it should reveal you shortname again but in Greyed out form which mean you Own the File/folder
Repeat this for each containing folder until the Library item on the left (you don't need to do the Little House  icon one)
You should have Read an Write Permissions and Own all of them.
Can you confirm this ?
8:04 pm      Sunday; June 15, 2014
​  iMac 2.5Ghz i5 2011 (Mavericks 10.9)
 G4/1GhzDual MDD (Leopard 10.5.8)
 MacBookPro 2Gb (Snow Leopard 10.6.8)
 Mac OS X (10.6.8),
 Couple of iPhones and an iPad