10.8.2: FaceTime + Messages: internal error, won't start

Question

Hello.
I've installed the 10.8.2 update and now I can't use FaceTime or Messages anymore. They won't even start up.
I always get this error message telling me that some internal error has occured and I need to quit and reopen the application.
I really need FaceTime and Messages on a daily basis. So this is a nightmare!
Before the update everything worked fine.
Every ten seconds(!) or so a new crash report is generated because some process called imagent crashed.
Here's the beginning of two crash reports:
Process: imagent[1120]
Path: /System/Library/PrivateFrameworks/IMCore.framework/imagent.app/Contents/MacOS/i magent
Identifier: imagent
Version: 8.0 (900)
Code Type: X86-64 (Native)
Parent Process:  launchd [159]
User ID: 502
OS Version: Mac OS X 10.8.2 (12C54)
Report Version:  10
Crashed Thread:  0
Exception Type:  EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Application Specific Information:
dyld: launch, loading dependent libraries
Dyld Error Message:
  Symbol not found: _OBJC_CLASS_$_IMInvocationForwarder
  Referenced from: /System/Library/PrivateFrameworks/IMCore.framework/imagent.app/Contents/MacOS/i magent
  Expected in: /System/Library/PrivateFrameworks/IMFoundation.framework/Versions/A/IMFoundatio n
in /System/Library/PrivateFrameworks/IMCore.framework/imagent.app/Contents/MacOS/i magent
and then one from FaceTime itself:
Process: FaceTime [357]
Path: /Applications/FaceTime.app/Contents/MacOS/FaceTime
Identifier: com.apple.FaceTime
Version: 2.0 (1080)
Build Info: FaceTime-1110000000000000~1
Code Type: X86-64 (Native)
Parent Process:  launchd [160]
OS Version: Mac OS X 10.8.2 (12C54)
Report Version:  10
Crashed Thread:  0
Exception Type:  EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Application Specific Information:
dyld: launch, loading dependent libraries
Dyld Error Message:
  Symbol not found: _IMCopyURLEscapedString
  Referenced from: /System/Library/PrivateFrameworks/FTServices.framework/Versions/A/FTServices
  Expected in: /System/Library/PrivateFrameworks/IMFoundation.framework/Versions/A/IMFoundatio n
in /System/Library/PrivateFrameworks/FTServices.framework/Versions/A/FTServices
[I didn't include the large part of the crash reports called Binary Images to keep this post short but I'm more than happy to do so if it's essential.)
What I have tried so far (without accomplishing anything at all):
- installed the 10.8.2 combo updater on top of everything
- deleted all preference files in my home library related to the imagent, ichat, FaceTime and Message (incl. the ByHost folder). And incl. the Cache folder.
- deleted all keys/entries in my key chain that are/seem related to FaceTime, Messages & imagent
- created a new admin user and tried to start FaceTime/Messages using this account
- I even repaired permissions (even thought this didn't look like a permissions issue).
I'm really  quite frustrated as I can't seem to repair this.
I hope somebody reads this and knows just what I need to do to get FT & Message going again. That would be so much appreciated.
Thank you.

Answer 1

Hi,
IMAgent is a support app tucked away on the "System" side of things that helps with Messages (or iChat 6 in Lion) and the FaceTime App.
Basically what it does is Login the accounts and "Listen" for Off Line IMs and calls
For Messages it will start up the App if a Messages is sent to any of your IDs or Screen Names.
For FaceTime it will start up the app if someone calls you.
It is this IMFoundation item that you need to be "reinstalling"
Expected in: /System/Library/PrivateFrameworks/IMFoundation.framework/Versions/A/IMFoundatio n
If this is the file you "replaced" I would do a Mountain Lion Recovery and reinstall the whole OS.
11:37 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